You stand with the jockstrap on in front of the mirror. "Magic" you snorted. Yeah right...
Though your cock did look bigger, you had to admit. Turning to the side, you admired the bulge your genitals made in the jockstrap. They looked bigger than they actually were, if you had to guess it would be around 5 inches fully soft. And as you watched, you could swear that your penis was still growing.
Looking down, you smiled at the sight. The jockstrap bulged thickly, strained by what now looked more like 6 inches of sock cock pushing the fabric out. Below which your balls hung. They were normally the size of ping pong balls but they looked larger in the jockstrap, they felt closer to the size of eggs. Man, it would be amazing to be that hung, you thought.
Curiously, you stick your hand inside the jock. Your cock even feels bigger! It couldn't be... no, you thought. Turning to the side, you notice that the jock is bulging more than it did previously. If you didn't know better, you'd swear your cock was 8 inches... soft! That would be amazing...
In fact, the jock is starting to feel constrained as if it's struggling to hold your cock. Or maybe your cock is growing inside of it. You shiver at the thought. So it really is magical! How big were you going to get, you wonder. Oh hell, you couldn't take it anymore. Curiously you take off the jockstrap.
Immediately your new 9 inch soft cock flops out and hangs down. It's also much thicker. Below which, your balls have grown to the size of tennis balls. It's obvious that the jockstrap really is magical!
Grabbing a pair of your regular briefs, you confirm that none of your current underwear will fit. Your cock is just too cramped, but the bulge looks fantastic. With an exciting thought, you realize that the jockstrap is the only underwear you have that will fit. Maybe you'll grow even bigger... you swoon at the thought. Is there a maximum to the growth?
Carefully slipping the jockstrap back on, you make sure it fully covers your cock and balls, much harder to do now they're that much bigger. Turning to the side, you smile at the thick bulge created by your pulsing cock... wait, pulsing! Your eyes widen as you watch it slowly expand in your jockstrap, realizing that it's still growing.
Turning back to the front, you eye the fabric. How long will it hold before the jockstrap rips? You'd rather not rip such an amazing item, but share the gift with others if you so desired. Sighing, you remove the jockstrap and are once again amazed. Even in such a short period of time, the jockstrap has grown your cock an additional 2 inches, bringing you to almost a full foot soft. Your balls have also grown to the size of apples.