"We should probably head inside," Cody said, looking at his now nude, eighteen year old friend.
"Yeah," agreed Jim.
Cody quickly grabbed the balloon and released its hold over Jim. Due in part to his muscles Cody was tall for his age, about 5'6'', and rather well endowed as well. Now Jim was six inches taller than him, but not quite as muscular, though still showed clear definition on his young adult body. "Still can't beat these babies eh?" Cody asked, flexing one of his biceps.
"Almost," said Jim, flexing as well and showing similar size, though ever so slightly smaller.
They were in Jim's room again and Cody almost immediately began to strip, and went down until he was nude. His endowment was of similar size to Jim's, though the latter was slightly larger. "Uh... what're you doing Cody?" Jim asked, looking over his friend's rippling frame.
"I wanted to age too, but I didn't want to ruin my clothes," explained Cody. "Alright, control my age."
With that Cody took a breath with his large chest and blew into the balloon. As it expanded, so did he, growing up from twelve to sixteen. Hair showed up around his endowment and to a much lesser extent around his belly button. He was older and more manly looking, and now stood about 5'10, only two inches shorter than his friend. And his muscles, of course, had expanded with him, and he was now clearly more muscular than Jim.
He blew in another breath and he aged another four years and here said release. He was now about 6'3'', a couple inches taller than his friend, and much wider. He looked very much like a serious weightlifter now, and possessed the muscular body to show for it. "Woah, this is awesome!" Cody said, hearing his deeper voice and flexing in Jim's mirror.
"I think you're a couple years older than me," Jim noted.
"Maybe, but only like, two maximum. I wonder what else we could do with this thing."