“Agh, I give up” Jim sighed. He’d looked through several cabinets and drawers and hadn’t found the ruler. Was there anywhere else left to search?
After feeling his underwear seem to get tighter, he decided that was it - he was going back upstairs. 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 and looked obscene, completely out of place for a 12 year old, and it was still growing!
Quickly Jim blew up the balloon to try and stop the growth, but some little part of him was stopping him, egging it on. How far could he let it go?
Before Jim could answer that thought, his shorts split on the middle seam, and Jim was left standing in his underwear. Determined not to let that rip too, Jim said “Control the size of my underwear” and blew into the balloon.
Once again, his underwear loosened as it grew larger. However, Jim’s cock was not to be outdone, and it continued to slowly pulse and swell. Jim blew again into the balloon, making the underwear even bigger. “Release” he said, satisfied for the moment.
Crossing the room to the dresser, Jim now had to walk with his legs wider apart to accommodate his bulge - which now looked like Jim had a basketball in his underwear, and still swelling. Searching his drawer, Jim could find nothing even close to remotely fitting for his new cock. He didn’t expect to though - who makes clothes for a 12 year old with a cock at least three times the size of an adult’s?
His attention was drawn back to the tightness in his groin. It was now so heavy that Jim had to sit down. By now it looked like he had a beachball between his legs, and Jim was forced to sit severely manspreading.
“Enough is enough. Control the size of my cock and balls” Jim said after blowing air into the balloon. He began to release it and was relieved to see his genitals quickly shrinking back to normal. When all of the air was out of the balloon, he smiled at them until he noticed something.
They were still swelling.
But he had shrank them! Already his cock and balls were once again on the large side for a 12 year old and slowly becoming more so. Jim realized he never removed the growth from his genitals, they would keep growing forever!
Jim considered it but then realized - he still had plenty of time to have fun. Besides, he wanted to try something. “Control the rate my cock and balls grow” he said, then let air out of the balloon. He relaxed when he saw his genitals stop swelling. Even if Jim was still enormous (he estimated a foot long soft) it was at least manageable compared to beach ball testicles.
Searching his drawer again, Jim found his baseball underwear and athletic cup from when he played baseball a year ago. The athletic cup was nowhere near fitting now, but his underwear might. He pulled it on and smiled - the extra room given for the cup allowed for it to comfortably hold his balls instead. Positioning his cock down a leg hole wasn’t the greatest, but he didn’t see a better option. Pulling on some loose basketball shorts, he admired the bulge. In fact, his cock head almost came out of the leg of his shorts!