"Fuck bros, feel so fuckin HUGE!" Sean bellowed. He flexed his monstrous arms, each easily over 43 inches, and moaned at the sheer size of himself. "Dude so BIG dude" was all he could say. He was a gigantic dumb roid head now, like the others, but even bigger and his new mass turned him on intensely. All the other guys stared mouths open, drool coming out of their mouths. Their small dicks were all rock hard and leaking pre. Blake waddled over to him and without a word started sucking on his bulging pecs, looking up he couldn't see Sean's face under all that thick beef. "Yeah suck those big muscle tits bro" Sean growled, his own cock now rock hard as well and pouring out pre. Derek noticed this and immediately began slobbering all over his roid cock. Licking up as much pre as he could, thick strands of it getting all over his beard. Thomas then joined in, wrapping his mouth around Sean's other bloated pec and sucking on it as hard as he could feeling the muscle with his tongue and face. Sean was in ecstasy he looked up at the mirror in front of him and saw these freaky roid heads worshipping his insanely huge muscle. He flexed again, each bicep larger than his head, traps engulfing the sides of his face, pure roided out muscle...he was so close to blowing his load. Then he felt a prick in his giant glute. Runt had snuck in and given him a second injection. As soon as he felt the roids fill his muscle he couldn't hold back he blew the biggest load of his life as he began to swell up even bigger. Not only that but his gigantic pecs that were inflating bigger and bigger and bigger by the second threatening to block his view started gushing out cum from the nipples too. Blake, Derek, and Thomas drank as much of his roid load as they could. Their distended roid guts filling up even bigger with all the gallons of muscle cum. Sean kept cumming and growing - so huge that his head was nearing the ceiling and his muscles were so insanely thick that his movement was becoming very restricted. But he fuckin loved it, "UHH BIGGER, MORE, BIIIIGGEERRRR!!!" he yelled in the deepest manliest voice. His muscles pushing against each other as they continued to swell, lats pushing his tree trunk arms out to nearly 90 degrees, his traps now fully overtaking his head, quads so thick he had to stand with his feet way apart, his glutes filling up like waterballons sticking out feet from his back. "ME BIGGER, ME GROOOOW!!!" he continued to yell, shaking the building with his deep voice. His cock began to swell in proportion too, thicker and thicker longer and longer it grew. It crept down to the ground reaching about three feet soft, a massive head leaking pre, and two watermelon sized balls churning with cum and testosterone.
Blake, Derek, and Thomas were drenched in Sean's cum, inside and out. All of them moaning in lust, huge dumb roid heads barely able to communicate but with grunts of pleasure. They then started to feel different, like energy welling up deep inside them, they felt primal and aggressive like they had overdosed on roids. Then they started to grow with the power of Sean's cum that was intensified by Runt's new steroid formula. Writhing around on top of each other they began swelling and moaning. "OH YEAH BRO, FUCKIN GROW!!" Derek growled. His neck was way thicker than his head now, his shoulders stretching out many feet from his body with thick roided mass. His pecs began pushing up against his chin, the cleavage between them deeper than two hands, his nipples becoming extra sensitive he reached for them. He was able to rub them for a moment, the feeling sending shock waves through him, but his biceps were growing so big that he was having trouble reaching now and soon wouldn't be able to at all. He was inflating with so much muscle that he could barely reach anywhere. Standing up he waddled over to the mirror to watch the growth. His monster ass bouncing with muscle and begging to be played with. He was so wide now he could fit ten grown men inside him and he was still swelling bigger. Lost in his growth he didn't notice Sean stomp over behind him until he looked up and saw him towering over him. Seans cock was rock hard again with all this hyper muscle growth everywhere, behind them Thomas and Blake were making out, shoving their tongues deep in each others throats while they grew and grunted and grew. Their pecs slowly pushing them apart but their lust keeping them slobbering all over each other.
Sean looked down at the now new immobile Derek. "BIG MUSCLE. ME FUCK NOW!" and with that he pushed Derek over so his giant glutes were up in the air. The crack between each swollen globe of muscle had to be about three feet deep and full of hair. Sean's freaky cock now fully erect stood at least four feet in the air, soaked in pre, he shoved it deep inside Derek's hole and started thrusting like a beast. "UH FUCK SO BIG SO BIG" he yelled as he plowed Derek as hard as he could flexing in the mirror while he did. Derek was helpless despite his own enormous mass. Sean was so much bigger and he was in heat. Derek just moaned as the muscle giant destroyed his hole. His own little cock so hard and on the verge of blowing. "ME GROW. ME BIGGER!!!" Sean kept yelling. Runt smiled, his plan worked, they were becoming addicted to growth and now was his chance to give Sean what he wanted. He crept up and emptied a huge syringe full of his most powerful roids in his ass and chuckled to himself. Sean felt the power flowing through him again, he bellowed so loud the ground shook. He looked up in the mirror and saw the growth beginning again. His traps and pecs engulfing his caveman head, his shoulders so wide they nearly reached opposing walls, his arms could barely flex with so much muscle mass but they had become so huge it didn't even matter, his glutes and quads beyond massive there was no way he'd be able to walk except maybe waddle a little, as his pecs began blowing up so big they started obscuring his vision he blew his load at his own freakish size. "ME MUSCLE!! ME GOD!! ME GRRRROOOOOOW!!!" he yelled with a voice deeper than thunder and filled Derek up with his insane roid load. He fell back and was still cumming everywhere, covering himself and the others, filing the room with his roided muscle cum while he moaned and grew. Nearly completely immobile with muscle but still roaring for more "MOOORRRE MUSCLE!! ME GRRRRROOOOOW!!!"