Looking through the drawers, Jim finally found a ruler. "Yes!" he cheered. Quickly, Jim closed the cabinet and tried to run out of the room, but he found that he couldn't. His groin was now so swollen that its mass swung around whenever he tried, so he was forced to walk. It felt painfully slow for Jim, especially as he could still feel his underwear ever so slightly tightening every second.
Finally reaching his room, Jim closed the door and finally walked over to the mirror and looked. His shorts, which had previously just shown a bulge, were showing an enormous bulge. It felt incredibly tight. Quickly Jim pulled off his shorts and then his underwear.
Out flopped a monster cock. Jim's new cock. It was still hairless and looked like a kid's, except for its size. It was enormous! Putting the ruler next to it, Jim saw it slowly swelling past the end! It was over a foot long, and still growing! Jim's balls were equally impressive. Each one was the size of a large apple, and also slowly swelling. Walking over to his dresser, Jim felt his cock swing heavily, and his balls knock against each other with their weight.
Grabbing the balloon, Jim was about to end the expansion, but then he felt tempted again to experiment a little more... "Control how much my cock and balls swell in size per minute" he said again, and blew another breath into the balloon, followed by "release".
If it wasn't obvious before, it was now. Jim could clearly see his cock slowly growing longer and longer. It was already down to his knees and still lengthening. Jim wondered what would happen if he simply outgrew his clothes? Couldn't he try that too? He didn't want to stop the expansion though...
Blowing a few breaths into the balloon, Jim said "Control the size of my cock and balls!" and then let the air out. To his delight, his genitals immediately shrank back to the size they were before Jim had started their growth. However as Jim watched, they were once again still lengthening. The first growth spell remained in effect!
Quickly Jim let out the final bit of air and his genitals shrank again. "Release" he said, and pulled his underwear up, Jim noted that his bulge was back to normal - though it was already starting to inflate again. He sat down on the bed eagerly watching as his underwear went from barely showing a bulge to average, to something a 12 year old should be proud of, before quickly going into the realm of insane. The underwear was stretching to its limit, as Jim watched it was starting to give...
With a massive RIIIIIIIIIIIIIIIIP, the underwear's seams ripped, and Jim's massive cock exploded outwards, extending to its full length and still growing. It was already at the length it had been before Jim shrunk it, and was growing past that.
Getting up to retrieve the balloon, Jim had a harder time walking as his growing balls weighed heavily on his groin. He managed to get the balloon, blew it up with two breaths, said "control how much my cock and balls swell in size per minute" and let the air out, sighing in relief as his cock and balls stopped expanding. "Release" he said.
Now to deal with this size, it's amazing but too much is too much! Jim thought. "Control my cock and ball size" Jim said, blowing the balloon up a few times, then releasing the air. They didn't shrink all the way, but Jim was left with a six inch softie that was much more manageable. That was fun! he thought