Luke thankfully managed to quickly extricate his key from the shreds of his clothes on hand, and unlocked the door in similar haste. He almost slammed it shut behind him and breathed a sigh of relief when he got inside. His mom and dad were both gone for the day at work, leaving Luke at home by himself. By his almost totally nude self. He ambled up to the upstairs bathroom, still unsure, still thinking somebody was gonna walk in and see Luke as he was now and freak the fuck out or laugh at him.
Entering the bathroom and locked the door behind him, looking into the mirror and seeing what had become of him.
His body had basically puffed up with muscles and size, and his face was handsome, decorated with a scruffy almost five o'clock shadow of a look, his muscles covered by a somewhat heavy coat of hair that never quite managed to obfuscate just how big and buff and toned he was. Luke had never imagined he was going to be this big, never imagined he would grow up this fast. And here he was now. Standing in the mirror and undeniably looking at a much bigger, much stronger Luke.
He was exactly 23, though he'd never be able to say that with the greatest certainty. And he was gifted with the body of a college going, muscular athlete. He was just astonished at how big he was now.
He flexed an arm and his eyes went wide. That...that had to be about 20 inches. He flexed it again and he felt his dick leak a little at the sight, making him adjust himself down there, almost swooning when his hand brushed against his now all too sensitive foreskin. He wanted to just go to sleep and wake up to see whether this was all a dream or not...but he also wanted to stay awake and examine himself more.
His new body was huge, and he now felt strong, stronger than he'd ever felt before. He flexed his chest and thumped it a few times, feeling the hardness and unyielding, concrete like thickness in his new body's chest. He grinned at himself and poked at his abdominals, each of them tense and strong enough to not yield even a little under his scrutiny...
...And then he looked down and saw what became of his manhood. Around eight and a half inches now, more or less fully erect down there. Luke shakily felt it and almost fell over from how sensitive it was under his caresses. He couldn't help it, and before long his manhood was wet with pre-cum and exertion from him awkwardly groping and feeling at it. He had literally no sexual experience, and was doing only what felt best.
He suddenly gasped and his cock emitted its load across the floor, some of it even hitting the cupboard. He had never felt anything half as good as that. And his mind was already acclimating and wanting more of that unique, incredible sensation. He was well and truly grown up now. And he guessed based on his look he was in his twenties. So...he could...!
He already had his cock back in his hand and he chuckled somewhat dumbly. He wanted to do that again. And maybe find someone to do it with!