Big Mac (Anthro) / Muscle Growth & Nipple PLay

Big Mac groaned as the shirt grew tighter around his chest. Just this morning, it’d been barely loose on him, but now he could see the outlines of his abs and chest muscles clearly through the fabric.

He grunted, his air supply being cut off by the tightening collar around his neck. Another stallion might have let his new muscles burst right through the fabric, but Macintosh was a practical stallion. He’d always been a larger pony than others, and he appreciated the value of a good large-sized shirt. So carefully, making sure not to snap the buttons off with his sausage-sized fingers, he opened the shirt up and let his massive chest breathe.

His pecs heaved as he sat back on his bed, his biceps swelling until his shirt sleeves seemed paper-thin. Every vein, every ripple of powerful, growing muscle was visible, but - thankfully, Mac thought with a sigh of relief - the seemed to have stopped for now. He liked this shirt.

He took a moment to adjust his posture to his new frame. He’d never had small pecs, but these new muscles jutted out from his chest like a bodybuilder’s. The only stallion he’d seen with a larger chest had been Bulk Biceps, and these put his to shame.

The muscles themselves weren’t the only thing that had gotten bigger. He looked down at his nipples and slowly ran a circle around them with a finger. His whole body shuddered at the touch, his nipples stiffening until they stood a good inch upright off of his already monstrous chest.

His fingers played with his nipples gently, softly rubbing, then flicking, then massaging their heads as his other hand slowly strayed down toward his crotch, where his powerful leg muscles stood ready to burst out of his pants.

Big Mac’s breathing became heavy, and not because of tight clothes. He closed his eyes and, for just a few moments, enjoyed the feel of his muscles rising and falling beneath his touch - not to mention another, more powerful muscle that had only just begun to grow.