"Growth Ce---Cer---um? What's that?---" Jaffar was cut off by the sudden tingle that spread over his body. He felt like he was getting bigger. Which was proven true when his pajamas became tighter.
"What's ha-happening!" Jaffar stammered, a bit shaken by his weird, new voice.
Jaffar moved into the bathroom and locked the door so no one would go in. He felt a twinge here and there, and saw he had grown to 7'2, just like his large father. His clothes looked too tight, or looked more like a tube top and tight-shorts. After his height was done, the growth spread to his muscles. This hurt just a bit, and made him feel very warm. His arms grew from a puny size to about eight-teen inches-round in no time flat. While his chest heaved out, tattering his shirt, to a nice 40 inches. His abdomen soon followed, as eight neatly lined stones pushed out. Along with that, his legs beefed up to support this new frame of his.
Jaffar stood there, looking in the full length mirror. He was awe stricken. His body was... gorgeous. The fact he would look that great when he was older made him feel estactic, to say the least. He eyed his genitals, it barely fit his new body. And the serum must've picked up on this and continued the growth. His little pecker sprouted out by six inches, the girth being 4 inches... This was flaccid. While his testicles grew further, to the size of grapefruits, ready to make plenty of man seed and testosterone for this god of a man.
Jaffar searched his new body, cupped his meaty chest, flexed his meaty arms, and rubbed his hard stomach.
"This thing could grate cheese..." He said in a deeper voice. Jaffar was now sweaty. And his new body now produced a different odor while sweaty. Jaffar didn't like it at all, so he jumped in the shower.
Soon his flaccid member started to get a bit overjoyed with the warm water spraying over it. It began to slowly harden. Jaffar was a bit aroused at this, but a bit scared. His old tool never did that. Soon the magnificent cock started get hard, pointing straight ahead since this was it's first time. Its veins snaring all around it, supplying the man meat with fluid. It's head grew a shade of red. It must've been at least a foot long, nine inches thick.
Jaffar didn't know what to do with it. But it's head, still growing a bit large and a bit more red every second seemed to call out. Jaffar took his palm and massaged the head. Which greeted this gesture by letting a shock wave of pleasure move through his tool. Jaffar liked this a lot. Soon he leaned back against the wall, having his breathing skip a few paces. He took both of his hands and wrapped it around his tool, vigorously jerking that new tool of his. It was excited about it's new test run as it would seem.
With a manly moan, Jaffar released his seed. He was astonished, but enjoyed the pleasure. And his cock shrank back down to normal size, satisfied with it's first run.
"Ah... Being grown up rocks!" The boy yelled as he got out of the shower. He prodded through his father's clothes and put on a pair of boxers. That must've been old because they were worn and tight. But Jaffar's new packaged like how they were cradled. So Jaffar was happy too. He put on a nice white under shirt that allowed his thick arms to show, along with his heaving shoulder. It was tight, so it showed the definition of his new torso. He also threw on a pair of long track pants.
"I wonder what Dad will say..." Jaffar wondered aloud, beginning to get a bit worried.