Amazon Maud casually embarassing Big Mac with her own big body (muscles and futacock)

“So you really lift that much?” Dash didn’t look convinced. “I don’t believe it.”

“Eeyup,” Big Mac said. “Care to see, Miss Dash?”

“Go for it, big guy.”

With a nod, Big Mac crouched down into a squat. His thick, corded thighs bulged against the fabric of his shorts, and his chest seemed even more impressive when it was straining against his shirt, his two thimble-sized nipples clearly visible through the dampened cloth. He rubbed his hands together, his biceps flexing casually as he did so, and reached down to get a good grip on the barbell.

Rainbow Dash’s eyes opened wider and wider as Big Mac, slowly but surely, lifted the barbell into the air. That thing must have been five hundred pounds, but, grunting and sweating as he was, Mac still looked to be more than up to the task of lifting it. With a final groan of effort, he got it up over his head and held it there, elbows slightly bent.

Big Mac just looked down at Dash and grinned. Every part of his body was flexed, bulging almost larger than life. He said one word: “Eeyup.”

Dash stared, then began to laugh. “Crap, Mac! You’re incredible!”

Mac’s grin just widened. Slowly at first, he began to pump reps with the barbell. He doubted there was another pony in Ponyville who could have lifted it, let alone pumped it with the ease he was currently putting out. One rep. Two reps. Three. He could feel his enormous muscles flexing and relaxing with each motion, and loved every twitch of his body. Somewhere between his legs, too, “Little Mac” was stirring. Macintosh had always gotten excited from a good workout, and he wasn’t about to let this opportunity pass up - especially with Rainbow Dash in here.

As he pumped, groaned, and flexed, his member chubbed up more and more, his balls swelling with cum beneath his straining gym shorts. Had he bothered to look, he would have seen the growing expression of shock in Rainbow’s eyes - and he would have loved it. There were few things in the world that Big Macintosh loved to be reminded of more than his size. Ever since he’d hit sixteen, he’d been the biggest stallion in all of Ponyville. While he’d never needed to bring it up, everypony had known it.

On and on his massive rod grew, chubbing up past six, eight, ten inches -

With a mighty roar, Big Mac lifted the barbell up over his head for his twentieth rep. Twenty! That must have been a new record for him! He’d never -

“Ooh! Dashie! Mackie!”

With a surprised grunt, Mac let the barbell drop to the floor. It hit the ground with a crash, shaking the entire barn. Some part of his brain silently gave thanks for the fact that he hadn’t dropped it on top of his feet.

“What the - “ he said. “Pinkie Pie!”

“Ooh! Yes! That’s me!” Pinkie positively bounced inside, her tall floppy hair springing and sproinging with every step. “I wanted you to meet someone!”

Mac just stared. “Who?”

“My cousin Maud! She’s visiting Ponyville from the rock farm!”

Rock farm. Cousin. Right. Big Mac remembered AJ mentioning something about this. Slowly, the shock of dropping the weight began to leave his mind, and a wry grin spread across his face. “Alrighty. Where is she?” He wondered what this “cousin” looked like - surely she’d be a heck of a lot similar to Miss Pie.

“Ooh! She’s right outside!”

“Then bring her right in,” Mac said, nodding. He reached around for a towel to wipe off his forehead. It’d be nice to meet somepony new.

Pinkie didn’t miss a beat. “Oh, Maud!”

Big Mac knew something was wrong when, the second the last word sang off of Pinkie’s lips, the floor of the barn shook. An enormous, grey-furred hand reached through the front door of the barn - from the top of the eight-foot opening - and, slowly, a mare’s featured bent down into view.

Big Mac stared, wide-eyed and dry-mouthed, as Miss Maud Pie squeezed herself through the door. At first, it was difficult to get an idea of her true size; as she bent over to fit through the doorway, she had to nearly double down to her waist. The size of her bust - bulging so far past her chest that had the barn door not been extra wide, she surely would have shattered it - left his jaw hanging and his cheeks even more red than usual.

“I - “ he sputtered. “Bwuh.”

Maud Pie slowly drew herself up. It was a long and arduous process, but from the way something seemed to be stirring beneath that tree-sized skirt, it certainly wasn’t unappreciated. At first glance, the mare’s features were nothing like Pinkie’s: blank, staring, carefully neutral. At second glance, they proved even more dissimilar.

Where Pinkie Pie was a bit squat, and more than a bit chubby, Maud Pie was absolutely covered in thick, bulging muscle. Each one of her biceps - unflexed! - looked to be even bigger than one of Big Mac’s legs. He’d spent years bulking those up. As she finally reached her full height, Big Mac felt his jaw drop even further. He’d spent years being the tallest stallion in Ponyville; a stallion with a height of six-foot-six could enjoy a very comfortable life looking down on the rest of the citizenry. But this Maud Pie absolutely towered above him! He must have just barely reached her nipples - her big, bulging nipples, some part of his mind noted, which each looked as large as his fist. Just meeting her eyes made his neck hurt!

As Mac gulped, twitched, and began to sweat, Pinkie Pie cheered and giggled. “Welcome to the Apple Farm, Maud!” she said, clapping. “These are Big Mac and Rainbow Dash! Though Dashie doesn’t live here.”

Maud didn’t really reply; instead, she just moved her head down a fraction of an inch. Then, without warning, she bent over, one gigantic hand outstretched. Those sausage-thick fingers looked like they were heading right for -

Big Mac jumped out of the way just as the amazon Maud closed her fist around his barbell. She hefted it up to her waist - almost to his eyes! - with all the ease of a toddler lifting up a rattle. “You dropped this,” she said, her voice a droning  monotone.

Big Mac gulped. He’d struggled to lift that damned thing at all, and here she was picking it up with all of the annoyance of swatting a fly! He eyed the muscles bulging and rolling beneath her tight clothes, and briefly wondered how he could have ever thought he was, in any way, “big.”

But that wasn’t the end of it. As Big Mac watched, the “stirring” beneath Maud’s skirt slowly became something a lot more concrete. It started with just the tiip, but soon, a full-size (if not oversize) cock began to emerge from between her legs, the fabric sliding down along its shaft as if it were nothing.

Big Mac’s sweating intensified as he watched that mountain of a stallionhood grow until it towered above his head. It must have been as thick around as his chest, and almost two-thirds as tall as he way! Maud just kept her eyes one him, still proferring the massive “weight” in one hand, as her lifting skirt revealed the two enormous, sloshing orbs between her tree-trunk thighs.

Maud caught onto the direction of his vision and raised an eyebrow. “Oh,” she said. “That’s just Rocky. He likes to come out sometimes.”

Just. Big Mac’s entire body quivered as he looked up at the mare who had outmatched - no, crushed - his very existence in every aspect possible. His muscles looked like straw beside her enormous, flexing figure; his size was laughable against a mare whose head just barely avoided scraping the rafters and who had to duck to fit through any reasonable door. His cock, though, throbbed and strained against his pants harder than ever, and in that instant Big Mac realized that the evidence of his own smaller, unremarkable stallionhood before this glorious pillar of masculinity was irrefutable.

And in that instant, he also realized that he was more turned on that he’d ever been in his life.

Licking his lips, still sweating, Big Mac slowly reached toward the barbell and grasped it in both hands. He steeled himself.

With an emotionless nod, Maud released her ironlike grip - and the barbell fell.