Futa Rainbow Dash and Lightning Dust hold a contest. First to burst their condom first wins. Winner cock vores the loser.

Rainbow Dash bit her lip and rubbed a little bit faster. Her cock, already hard and throbbing, was just beginning to drip pre into the super-sized condom she’d pulled over it. She could feel her balls swelling between her legs, pushing them slightly apart as her arousal steadily rose.

She glanced over to her side. There was Lightning Dust, her own twenty-inch stallionhood standing a good three inches taller than Dash’s own. Though Dust’s massive, musky balls were a good two inches smaller in radius than Dash’s, an observer never would have guessed it from the way her nuts churned, and swelled.

Dust was really getting into it, every part of her body swaying and grinding against her cock. Her own condom, the same size as Dash’s, flapped against the side of her cock with each jerking motion. A line of drool running down her chin, Lightning Dust moaned. When she came out of it, she looked Dash straight in the eye and smirked.

Crap. The winner had to burst their condom, and Dash wasn’t even close to orgasm yet. Meanwhile, Dust looked like every part of her body was singing with erotic energy. Dash closed her eyes and went to town.

Her hips jerked back and forth as she humped her own chest, her fat medial ring slapping against her stomach. Her breaths got shorter and shorter, a few more spurts of precum erupting from her tip. By now, there was a noticeable puddle of precum at the bottom of the condom - but Dash knew that it wasn’t anywhere near enough to win.

Soon enough, though, she felt it: that mounting, warm tension at the base of her cock, her swelling balls pushing against her legs harder and harder as the pressure mounted. She bit down even harder, her rubbing increasing in intensity. From the sharp breath she heard, it sounded like Lightning Dust was getting close to. That just spurred her to go faster. She wouldn’t lose. She couldn’t.

With a grunt, she felt the tension break - and then she was cumming, her hips jerking and twisting as she rode her orgasm out. Thick ropes of cum flooded her condom, doubling the puddle of pre in less than a second. But she was just getting started.

Dash grunted again, moaning as sweat started to drip down her forehead. She was cumming harder than ever before, halfway out of necessity, and halfway out of arousal for what would happen after she won.

Or if she lost, some part of her whispered, but she ignored it, her hips jerking and her cock throbbing as more and more cum flooded into the condom -

The condom was full now, and it was starting to strain beneath the weight of Dash’s milky white seed. Squinting, she eyed Dust’s condom - and gulped when she saw that it was bulging even larger than hers. She began to breathe heavily as she pumped harder at her own leaking cock. Her flood of cum redoubled, her hooves milking every last litre of seed out of her productive, swollen balls.

The condom was swelling up faster and faster now. It had be at least half again the size of Dust’s, from what Rainbow Dash could make out from the corner of an eye. Her cock throbbed and flared as the expanding condom, now near three feet across, steadily pivoted her body forward with its weight. Finally, just a second before the bottom of the condom hit the ground, it burst.

Dash flinched back as a wave of cum splattered all over her face. She rode out the rest of her orgasm licking the spooge dripping down over her muzzle. She could already feel the afterglow spreading throughout her as the final thick ropes of cum spewed from her flared head. Then she looked at Lightning Dust and grinned.

“No,” Dust breathed, her own hips jerking ineffectual as her own orgasm finished. Her condom still hadn’t burst. “No - I want a rematch! You can’t!”

“Sorry, Dust.” Dash’s voice didn’t sound sorry at all. “But those are the rules.” And with that, she touched her enormous head to Lightning Dust’s, moaning softly as her cockslit spread wide to encompass the girth of Dust’s own stallionhood.

“You c-can’t,” Dust moaned, trailing off as the sensation of Dash’s cock enveloping her own spread throughout her entire body, intensifying her ongoing orgasm. Her grin spreading, Dash took a step forward. She grunted with pleasure as more and more of Dust’s cock fell into her own. The condom actually slipped alongside it, the rubber pulled along by friction with the surface of Dust’s shaft and the inside of Dash’s. Rainbow’s eyes actually rolled up toward her head as the fat bulge containing Lightning Dust’s condom was swept up inside of her thick, groaning shaft.

By the time she’d reached Dust’s base, the condom itself had dropped down toward her balls - and burst inside of them. She grunted as more than a dozen gallons of Lightning Dust’s cum splashed down to join her own, making her shrunken pond of spooge back into a lake.

Dust was powerless to resist as the suction of Rainbow’s shaft forced her back legs behind her back, her whole lower body being hungrily gulped down into Rainbow’s. Dash just grinned and stroked her enormous, throbbing shaft as it consumed more and more of Lightning Dust’s body. Her balls were already groaning when Lightning Dust’s cock joined the rest of her orgasm, sputtering out a few weak blasts of cum before going entirely limp. Soon, more than half of Lightning Dust had disappeared inside of Dash’s cock.

Soon, she’d be nothing more than an ocean of seed to fill Dash’s enormous, sloshing, musk-covered balls. And once that was finished…  

There’d be no doubt whether Dash could break a condom or not.