You feel your nuts start to grow, soon filling up your hands. You let go as your balls grow, marveling at their size so far. It feels like they're the size of softballs, but still growing. As your nuts grow, you feel your dick fill up with more cum, making it drizzle even more all over yourself. It doesn't bother you, in fact you actually enjoy it some.
Directing your attention back to your nuts, you feel them grow to the size of basketballs. Enjoying the feeling of your large testicles, you rub them gently. A soft moan escapes your lips, but you don't stop. You rub a little more as you feel your balls swell more, making you moan a little louder. You keep feeling yourself up, revelling in the sensation of your balls pushing your legs apart. You keep moaning lustfully, not caring if anyone hears. You give a small yelp of surprise as your balls get a growth spurt, now reaching the size of over-filled beach balls.
You spread your legs as wide as you can, giving your testes plenty of room to grow and swell with cum. You feel them grow a little faster with more space, making you moan loudly as the sensitive skin is pushed hard against the bed. You notice that you're starting to rise, making you wonder how big your balls are at this point. It doesn't matter, however, as you lose yourself to the ecstasy, moaning loudly and lewdly. You feel yourself grow larger and larger, eventually stopping. You look around, seeing that you have crushed your bed flat, and that they're roughly the size of your breasts.
You look back up at your dick as it grow larger, pushing against the ceiling as it grows. You watch as it elongates, rubbing across the ceiling until it reaches the wall, leaving a smear of sperm. You can't help but masturbate, making it so that your dick starts slightly vibrating, holding in all of that cum. Just about as you go in for the blow, you hear a giggle. Looking to your right, you see your step-sister Jessica and your new girlfriend Sandy standing there with a bucket of popcorn. Your face reddens when you realize that they must've been standing there for awhile.
"Well Anon," says Sandy, "I see that you're enjoying yourself. I've been talking with Jessica about your... sexual behavior. I have to admit, I'm liking it! Now, let's change you even more before I go home. And don't worry, I made it so no one would notice what happens in here, and that no one would come in here. The only exceptions are us three."