Jim entered into his bedroom, closed the door and started to take off all of his clothes until he was completely naked.
Then, he looked for the balloon in his pocket and grinned. "Control my age and muscles!" He said before he started to blow on it.
The first blow made him grow almost an inch and a little bit of muscles. And he kept growing like that for a few blows until after one he felt something going on in his crotch.
When he looked down, he could see how his balls were finally dropping and he was getting his first erection. The next blow started to put hair on him and it kept sprouting like Play Doh noodles with the next ones until he was sporting a thick bush on his bigger dick and balls.
He was so focused on his genitals that he didn't see that had grown hair under his armpits, on his chest, around his nipples and even on his feet. His legs and arms had got thicker hairs too. He wasn't a kid anymore.
However, he didn't feel as big as Isaac used to be and he kept blowing, pumping his muscles and getting his last inches of height. After that, all that he was growing was weight and body hair. He ended up as really hairy muscle freak that has left teenhood a lot of years ago.
"Mmm, I think I exceeded." Jim said in a way more deeper voice than his own father. "I have an idea!" He said and took a pair of Isaac's shoes. He tried to put them in but his feet were too big for them, so instead he inflated the balloon first.
"Control my age and muscles." He said before he released some air. He age down until he thought he could fit in Isaac's shoes. "Let's try again." He said in a more youthful way before he put the shoes on. "Excellent." He smiled because the shoes fitted him perfectly. "Now, I need some clothes..."
He took some Isaac's clothes but they weren't too clean. "Now I see why he was looking for only one shirt. All these clothes smell bad!" He wore the less smelly ones, blue boxer briefs, black jeans and a gray sleeveless shirt that let him show off his newly grown muscles and his bushy armpits, by the way. Fortunately for him, Isaac's clothes fitted him, a little bit tight but fitted him.
To don't be seen by Isaac or his parents, Jim sneaked through a window and he managed to get out his home. He ran across the streets until he arrived to the movies.
"Ok, who looks like the leader of the cheerleaders?" Jim told himself while he looked for his brother's date. He found her next to a popcorn machine and she looked kind of annoyed.
"Hey, Isaac!" She called at Jim and he smiled at how convenient it was that she had mistaken him with his brother. "I've been waiting so long. Weren't you the one who was insisting with this date? Luckily for you, the movie hasn't started yet."
"I'm sorry, I had some troubles at home with my little brothers." Jim replied and giggled a little when he thought of Isaac's actual condition.
"I know. You complain about them all the time. Especially of the one who shares bedroom with you."
"Yeah?" Jim was a little pissed off by that. "Well, I recognize I'm not the best brother. I'm very rude and stinky. I can't even find a clean shirt for this date." He raised his arms and exposed his hairy armpits.
"Well, you're honest." She smiled. "And I like that." Then her smile became a little lusty when she noticed how beefy Jim's arms were. "Also, I kind of like jocks and it's obvious that you're doing exercise." She sniffed one of Jim's armpits before he raised down his arms in shame. "I'm a cheerleader, remember? The locker room smells worse."
Jim didn't understand, he wanted that she disliked him but she seemed more interested on him now. And he was more interested too.
"Come on, the movie is going to begin." She smiled before she took Jim by his beefy left arm. "I don't want to miss a second"
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After a few hours the movie ended, however Jim barely knew what it was about. He spent almost all the time sharing lips with her, occasionally feeling her tongue inside his mouth. She was rubbing his bulge all the time while she told him lustful things like she wanted to know if he's nasty down there too or how do he looks with a singlet.
When they came out of the theater, she was firmly holding Jim's arm, no matter if he was nervously sweating so bad all the time.
"You know that I was using you to make my ex boyfriend jealous." She told him. "But actually, I enjoyed this a lot."
"Me too." Jim replied. "It's the first time I experience something like this." He was meaning about his first date in his life but she understood something more romantic.
"Give me your phone number." She told him and he obeyed.
"I thought you only gave your phone number for the second date." Jim innocently said and she just grinned.
"That's true." She smiled at him. "My friend Nina will throw a party tomorrow." She took a selfie and sent it to Jim. "Pick me at 8 and bring your trunks. Nina has a huge amazing pool and I want to see more of your rude and stinky self in the water, ok?"
Jim didn't say a word, he just blushed and nodded. Then she kissed him goodbye and left in her hot pink convertible car. "Shit, I need to learn to drive." Jim said and immediately got stunned by how similar to Isaac he sounded.
He walked back to his home, thinking about what he's going to do. He'd planned to keep Isaac as a kid just for today but now he wasn't sure about that. After what happened in the movies, he really wanted to go that party. He didn't know what to do.