That night before bed, Evan lifted weights again. He stood in his room, shirtless, not even bothering to count his reps. All he knew was that with each rep he got hornier and hornier. The new amounts of testosterone flowing through his body were intoxicating. He felt amazing and he didn't care why.
With each rep his dick got harder and harder. He set the weights down, his workout shorts stretched to the max. He started to walk to the bathroom to take care of it when he noticed the potion still sitting on his dresser. Evan felt good. He felt powerful. He was taller, more muscular, and best of all way more hairy. Just what he wanted. He always wanted to feel this good. So before he could even realize what he was doing he had reached out, grabbed the potion, and drank a massive gulp. The vial was now half empty.
Evan was still rock hard, so he went to take a post-workout shower. He had a hard time getting his shorts off over is massive erection. The hot water poured over his furry body as he wrapped both hands around his newly enhanced dick and began to pump. It didn't take long for the complete ecstasy to overpower his body as he came. It was the most spectacular orgasm of his entire young life due to the fresh potion flowing through his body. The orgasm, in addition potion caused his body to grow right there in the shower. As he shot his load all over the tile walls of the shower, he inched taller, more hair grew on his body, and he even felt his dick thicken in his hands.
Evan got out of the shower, ducking his head to avoid hitting it on the curtain rod. He looked in the mirror and smiled at the behemoth he was becoming. He figured he must be 6'3" at this point. His beard had grown in so much that it would have put most adult men to shame. His chest muscles had filled out a bit more, but the hair had grown in significant, covering his newly toned pecs with a generous layer of brown hair. As he dried himself off, he noticed how heavy his legs and feet were. He figured they had to be a size 12 now.
Evan didn't bother with pajamas, they fit his puny body before, but he knew they'd never fit now. He found a pair of compression shorts in his drawer that thankfully stretched enough over his legs and dick to cover him. Despite having just cum, the tightness from the shorts aroused him again.
Evan laid down in bed, his newly enlarged feet dangling off the end. "The quicker he went to sleep, the quicker he would grow," he thought to himself. All that growth had happened in the minutes after taking the potion. Evan wondered what he would look like in the morning, especially considering how much of the potion he had drank.