"A little higher...no, just over the ridge...a little more tongue..."

Horizon's eyelashes fluttered as Tiller ran his tongue up the length of his massive cock, sensually licking Horizon's flare. "Just right..." Horizon murmured.

Tiller had worked on the Acres since before Horizon had gotten here. He was fairly popular with the mares, too—strong build, thick, tall frame—but if there was one worst-kept secret on the entirety of the farm, it was that Tillerhole was as gay as Hearth's Warming Eve and as flaming as the Sun above.

It'd been scarcely fifteen seconds after making eye contact with the other stallion that Horizon had caught Tiller down on his knees, tongue dangling from his mouth as he begged to see Horizon's endowment. One thing had led to another, and soon enough the two found themselves in the back of the grain silo, with Tiller's lips planted firmly around the tip of Horizon's stallionhood.

It was almost scary, Horizon reflected as Tiller ran a train of kisses and soft slurps down the length of his throbbing member, how massive his sex appeal seemed to be now. He'd known that news travelled fast, but he'd never expected it to have this kind of impact. Sex in Equestria might be a bit less formal than in the other nations, but it was still a surprise when the first words out of another stallion's mouth were, "I need to suck your cock."

So there he sat, imprisoned by light pleasure as Tiller's tongue ran up and down the length of his cock. It throbbed happily under the attention; standing at just over two feet already, Horizon's erection seemed to lap up each of the other stallion's licks with a new pulse of blood into the massive member.

Horizon moaned again; wherever and however Tiller had been educated, he knew how to give a blowjob like nopony else. Even on a cock as large as Horizon's, the other stallion seemed undaunted, slurping up and down the sides and opening his mouth so wide—so as to just fit the flared head in—that it seemed he'd unhinged his jaw.

Horizon felt a surge of pleasure, an overwhelmingly warm sensation, as Tiller opened his mouth even wider and pushed himself down on Horizon's dick until it had was brushing against the back of his throat. Horizon could hear Tiller's jaws cracking as his monstrous cock forced them ever wider, the stallion's warm mouth moist around his length as Tiller's tongue played and danced around Horizon's girth.

As Tiller slowly moved his head up and down what little of Horizon's length he could fit down his mouth and throat—an astonishing six inches, which was just incredible given the volume of Horizon's cock!—a small smile fluttered across Horizon's face, his eyes still closed in bliss. The oral sex had already spurred him on: his horn was glowing a light green, as if, by reflex, his magic knew that a pleasured erection meant that something, somewhere, was about to grow.

Horizon had barely contemplated another stallion going after his cock; after all, he'd been too busy drowning in pussy to even think of it. Now, though, with Tiller's thoroughly skilled mouth pleasuring his length, Horizon began to wonder which part of his anatomy he could grow. It had to be something new, he decided; something that would make the whole experience that much more intense. Stallions certainly didn't have breasts, though; nor did they have marehoods whose depths could be grown until Horizon's entire length—all two feet in length and over a foot in girth—could fit inside. His eyes swept over Tiller's own stallionhood: a respectable—though puny compared to Horizon's—seven inches.

He couldn't deny, though, that he enjoyed his status. He could grow Tiller's cock, true, but then there'd be two hyper-endowed stallions on the farm, and while he liked to think that he didn't have too much of an ego, it was easy enough to admit that he wanted to retain his status—and therefore reputation—just a little bit longer.

Horizon smirked. Who said he had to make Tiller's entire cock bigger?

His horn flickered as Tiller's licks increased in speed and pressure, his mouth caving in around Horizon's cock. A mixture of saliva and fat drops of precum leaked from Tiller's muzzle, dripping down Horizon's stallionhood with each thrust of Tiller's throat around it. As Tiller continued going to town on Horizon's cock, a light green glow sprung up around a certain part of his own anatomy.

Tiller moaned gently, feeling his balls be gently massaged as he slurped around the flare of Horizon's dick. It was an odd, tickling sort of sensation: it didn't hurt, really, but it was a light pressure that made them feel a bit heavier against his thighs. Then heavier. Then—

Tiller took a moment to pull his head off of Horizon's cock, his mouth coming free with a wet-sounding schlop. His balls still tingling, Tiller glanced down with saliva and pre still dripping from the sides of his mouth. His eyes widened. His balls were already nearly twice their normal size. His stallionhood, which had been resting on them as if they were a pillow, was slowly rising even further into the air as his testicles expanded.

And they were still growing. Tiller's jaw dropped as his balls—still growing a bright green—surpassed the size of nectarines in size, moving on to pass apples, and then even oranges in volume. He moaned, Horizon watching with smug satisfaction, as the amount of unspent cum filling his balls doubled, and then doubled again, churning and stirring a deep need inside of him to spill his seed.

"You..." Tiller grunted, his hooves hovering above his balls as though he was scared to touch them. "You're doing this? Just like with your—?"

"Yup." Horizon shot him a grin, running a hoof down his own massive length before letting it come to rest on his enormous balls. They sat between his legs, his own seed still splashing against their insides. "Just sit back and enjoy."

Tiller watched in increasing amazement as his balls grew and grew. He could feel their weight on his hind legs, their size almost pushing his thighs apart. They were the size of soccer balls, now! The only bigger ones he'd seen were on Horizon's stallionhood! Suddenly worried, he glanced back up at Horizon.

"Shouldn't my, uh, dick be growing too? Is there something wrong?"

Horizon shook his head, still grinning. "Don't worry—we're just sticking to one body part, for now. But you should start feeling it right...about...now."

Tiller gasped, his head going back as his balls surpassed watermelons in size. They were even bigger than Horizon's own, now—if he were to try to walk across the room, they'd nearly drag along the floor, carrying his churning seed every step of the way. At the very thought, a few drops of pre spilled from his dick. They were much larger than what he'd had before: In fact, one drop of pre, leaking from his tip, was fuller and whiter than his entire orgasm would have been before! His eyes opened even wider. His dick felt so full, with every drop pushing against his girth with its sheer volume. He glanced down at his balls and gulped; he could barely imagine the gallons of cum that waited in their depths.

He suddenly felt lightheaded, along with a powerful warmth that seemed to spread from his crotch until it filled his whole body. "I...I need..." he grunted, closing his eyes. He'd never felt this horny before—it was like an all-empowering need to fuck or to be fucked. All thoughts of life or anything else had fled from his mind, leaving behind only the gallons of cum churning in his balls and a powerful need for sex.

Tiller met Horizon's eyes, tensing his dick and unconsciously thrusting his hips toward Horizon's throbbing member. "I need to fuck you," he whispered.

Horizon blinked. Now this was something new. His eyes flitted down to his crotch—or, more accurately, to most of the way up his chest. After his own transformation, he'd gotten used to being the one on top; after all, what was the use of a gigantic cock if you didn't actually use it? Fucking, pumping ponies full of gallons of warm, steamy seed—that was what he did.

But apparently, Tiller wanted to try something else. And try as he might, Horizon couldn't find anything within himself that might object.

He glanced back down at the tip of Tiller's cock and licked his lips appreciatively. It was a nice cock—about the same size that he'd been before, if not a bit bigger—and it had a nice girth that he was...

He swallowed. ...That he was already imagining thrusting into his rump.

He looked over Tiller's giant, throbbing balls. Those nuts were, by now, larger than Horizon's own, constantly pumping thick streams of precum from Tiller's tip. It was no wonder the other stallion was so completely horny: The sensation and drive had to be more intense than anything he'd ever experienced! A small smile crossed Horizon's face—it was so often that he was the one giving that he couldn't help but wonder what it'd be like in the receiving end of one of those titanic horsecocks, filled to bursting with such a volume of semen.

Horizon met Tiller's eyes. "Okay," he said, quietly. "Just...go slowly, okay? I've never done this before."

Tiller bobbed his head up and down, eyes still wide. It was clear that he didn't care what he agreed to, so long as he was able to achieve release. Hesitantly, Horizon stood up, his own two-foot member heavy between his legs and his own engorged balls smacking against his sides, and turned around to present his virgin ass to Tiller.

He shivered as Tiller approached and began to run his hooves over his flank. Horizon didn't have a strong, or "sculpted" frame, but he'd done enough farm work on the side to at least have a lean, attractive backside. Tiller was taking a surprising amount of care, he realized—he hadn't just gone straight in. Still, the feel of the other stallion's touch was electric, Horizon's own dick expelling a thick glob of pre in excitement for what was to come.

Horizon grunted at a sudden pressure on his flanks, and then on his back. Tiller had raised his front hooves off the ground, getting ready to mount Horizon's backside as though he would a cart. This close, he could feel Tiller's massive balls pressing against the back of his legs—the backs of his hooves, even. In a moment of silence, just before it would start, he could feel the churning of semen from their giant depths, almost hear the sloshing of semen as Tiller's balls cried for release.

And then Horizon felt it: a pinpoint of pressure against his rump. It squeezed between his cheeks, probing gently toward his hole. He could feel it throbbing in need, slick as it was with pre. There was no doubt, at least, that it'd be highly lubricated: Tiller's balls were still putting out a tablespoon of precum a minute, and there was no doubt that there was more where that came from.

Horizon remembered the size of Tiller's balls, and then felt again their weight against his legs. A lot more.

Slowly, Tiller pushed against Horizon's ass, hooves guiding his cock into his asshole. Horizon let out a little squeak, giving a jerk of his hips as Tiller entered him for the first time, his well-lubed cock spreading his ass as it entered his virgin asshole. It may have been only an inch or two, but he could feel it inside of him: warm, full, and pushing against his slick walls. He remembered Lilydale and how wonderful, how tight, how arousing her ass had felt to him. Even with such a smaller cock—his own dick gave a throb of appreciation at the reminder—was that what Tiller was experiencing what now? That slow draw into a hole, but alongside a need to rut, to thrust, to fuck.

He let out a gasp as Tiller, perhaps unwilling or unable to wait any longer, thrust further inside until at least four or five inches of his cock were held by Horizon's ass. The curve of Tiller's balls, hanging heavily between his legs, pushed harder until they spread his ass for Tiller's view. Pre oozed out of Horizon's ass and down the sides of Tiller's cock, waiting patiently for the act to begin.

"Oh," Horizon murmured, feeling Tiller slowly slide a few inches out, and then back in. He was testing the waters, it seemed—seeing how well he could fit inside while inside Horizon. It seemed that he fit fairly well, which was a relief. For a moment, Horizon wondered at Lilydale's ability to take his immense size—even this much cock felt so tight to his unexperienced ass; what had his monstrous dick felt like while it was inside of her? Fill me up, she'd said. I want to take all of your cock.

And he wanted, he realized, to take all of Tiller's.

Tiller's dick slid an inch back until just the flare of his cock was still inside Horizon, pressing against the sides of his hole as his dick seemed almost to salivate pre onto the floor. "That feels so good," Horizon moaned. Tiller slid slowly in, and then back out. "So good..."

And then Tiller jammed his dick into Horizon's ass, thrusting so far up that he fully hilted his cock in Horizon's prime rump. Horizon let out a yelp—a squeal—as the sudden mass filled his rear, all seven inches pushing up his tract and dripping pre into him.

Tiller had gotten tired of waiting, it seemed.

Horizon's ears were filled with grunts, methodical groans as Tiller pulled out just as quickly before thrusting again. And again. Wet smacking sounds filled the loft as Tiller pounded Horizon's rump with every thrust, his massive balls, still churning with unspent pony cum, slapping against the backs of his legs.

Horizon moaned. "More..." he whispered, almost without even realizing it.

"What...was that?" Tiller grunted, hilting his sword inside of Horizon again. Horizon's eyes screwed shut: He wanted that pressure, that force inside of him—no, he needed it. "I...couldn't...hear you..."

"More!" he cried, leaning down lower to the ground until his massive dick was scraping against the ground, his balls smacking against each other as he presented his ass in full for Tiller's pleasure.

The other stallion wasted no time in taking his gift.

"Then...take it!" Tiller roared, and thrust even harder, even faster inside of him. Horizon's pupils became pinpricks as Tiller's girth pushed his tender asshole even wider, spilling additional spurts of pre inside of him and making each thrust come easier and more quickly. His breaths became heavy, the need for sex, to be filled dominating his mind.

Horizon jammed his rump backward just as Tiller thrust forward, the combined forces pushing Tiller's cock even further up Horizon's ass until it pushed against his inner walls. Horizon's eyes went wide: Tiller had found his g-spot, massaging and pressuring it until Horizon felt so filled with pleasure and desire that he was ready to burst.

In and out. In and out. It was like an endless cycle: Tiller would ram his cock deeper into Horizon, his throbbing cock almost vibrating his g-spot with primal need and lust, and Horizon would gasp and clench even more tightly around Tiller’s member. His cheeks clamped harder, increasing the sense of tightness and fullness. Horizon was pierced on Tiller’s dick, the latter’s balls slapping against his rear and teasing him with their seed-filled depths with every thrust, and he loved it.

The rate increased, the pleasure moving into a crescendo. Each of Horizon’s grunts echoed in the loft. He could have never before imagined the sheer sensation of taking a cock—perhaps at one point, he would have deemed it “for mares only,” but by Celestia, this feeling was so amazing that he would gladly experience it every day.

“Take it!” Tiller said again.

Horizon moaned; precum was dribbling from his tip at a faster, thicker rate. His taint convulsed, tightening and releasing with every heartbeat, his dick tensing and thrusting into the air with each pound of Tiller’s cock against his tender flesh. The pressure—that familiar, forceful pressure—was building up at the base of Horizon’s cock again, his balls churning as they pressed against Tiller’s own, even more massive testicles.

“F-fuck me,” Horizon choked out. “Fuck m-me harder.”

Tiller obeyed without a second thought. Then—

“I’m cumming!” Horizon moaned. He could feel the cum pressing against the sides of his balls, sloshing as it channelled its way up his dick—

“Euragh!”

Tiller let out a cry even as the words left Horizon’s mouth—and the precum stopped.

Horizon’s eyes widened.

With Tiller’s cock still fully hilted inside of his ass, Horizon felt a tighter…something pressing against his hole. It was thick: hard, and with a much, much wider girth than the rest of Tiller’s member. He groaned as it pushed and pushed against him, the force building behind him.

At the other end, Tiller was feeling a pleasure that he’d never felt before. Every orgasm that he’d previously experienced had been like a jolt of electricity: a sudden gasp of pleasure that sent shivers running up his spine. This was difference. His balls—his massive, gigantic, swelling balls—felt almost alive in the sheer power of their unspent seed. This orgasm came on less as a jolt and more as a rising tsunami, pushing against the base of his dick as though it were a hurricane trying to break through a much smaller dam.

He let out a cry, his back arching, as his seed broke through, flushing through his length and building up in a knot behind Horizon’s tender asshole with monstrous force. The pressure built up more and more, Tiller’s dick swelling out wider than he could have ever imagined as only a bit of cum leaked through, his balls supplying more and more until it burst—

And burst it did. With another cry that sounded like the moan of a dragon in heat, Tiller felt all of the pressure flood through his dick and rocket out the tip, rushing straight into Horizon’s ass and filling him with his thick, steamy seed. Horizon moaned as he felt it, yet for Tiller, it was an unfathomably powerful experience. He was barely aware of Horizon’s own cock spilling pints of cum onto the ground, its two-foot length throbbing in the throes of orgasm, as his own took him and held him tight.

For Horizon, his balls had grown with his cock, so even when one of his titanic orgasms overtook him, there was enough increase in space and volume to be able to handle it in what was, at the very least, a mostly similar way to what he’d had before, albeit with much greater sensation.

Tiller, on the other hand, had retained his “small” cock even through the growth process. With gallons of cum bursting from his balls, there was only a singular, tight channel for them to flow through. His breaths came in short, labored gasps, his eyes nearly rolling up into his head as the pleasure—that feeling of tightness that filled his cock. It was an impossible, enormous force—something that couldn’t be contained—and with each pump of cum into his dick and down its length, Tiller felt like his member was about to burst.

And burst it did.

His hips rolling, thrusting, and pounding into Horizon’s ass, Tiller’s cocked pumped pint after pint, gallon after gallon of thick, warm seed into him. Horizon let out a cry, feeling Tiller’s cum fill him up from behind. It was an unstoppable force: a wave of seed that crashed against his insides until it filled him completely.

And yet it continued on, Tiller’s balls spilling more and more inside of him until Horizon felt like he could take it no more. He felt cum sloshing inside of his gut, travelling all the way through him until it reached his stomach, swelling him outward and filling him even further.

Horizon’s stomach swelled, the pressure building inside of him as his own orgasm subsided, though Tiller’s continued on—redoubled, even, it seemed, with even more force and cum than he would have thought believable. Those enormous balls pounded against his back as his stomach grew and grew and grew, filling with seed until it hung low beneath him, his skin and coat straining as his gut filled with more and more pony cum.

After what felt like an eternity, Horizon felt the flood begin to subside. His stomach groaned, hanging so low beneath him as to push his massive dick to the ground, masturbating it further and coaxing out a few more spurts with its weight and size. It bulged out, pushing against his thighs and weighing on his balls as gallons of warm seed sloshed inside of it. With a grunt and a moan of pleasure, Horizon, completely spent, dropped to the ground, his full stomach squishing beneath him.

Tiller slowly pulled out of him, the last remnants of cum dribbling out of his tip. He was panting, his formerly engorged balls looking oddly shrunken, even though they remained a good three times their original size.

“...Wow,” was all he could say.

Horizon closed his eyes, loving the feeling of being full. It was something he’d never contemplated before—he didn’t even have a stomach ache. Instead, he felt warm, holding every ounce of Tiller’s seed inside of him like he imagined Chestnut and all the others had for him.

“Wow,” Tiller said again, gazing down at his still-massive balls. “That was…”

“Incredible?” Horizon offered, still lying in wonderment on his swollen gut. “Wonderful? Amazing?”

Tiller looked up, looked down, and then back up.

“...Yeah,” was all he could say.

Then he blinked.

“Wait,” he said, staring down at his gigantic sack. “How am I going to deal with this? I can’t walk around with two giant nuts hanging off of me all the time.”

Horizon smirked. Idly, he wondered if Chestnut would be in her lab right now.

“Oh, don’t worry,” he said lightly. “I might have just the solution for that.”