"Well, why don't we try our new experience with your new body?" You reply as you lean toward your former girlfriend who is currently a 10-year-old boy. "Look, babe. I know it's wrong and weird, but I want to try something kinky while you're in the form of a little boy. After this, maybe we can try something else."
"It's okay, honey. I'm fine with that." Your girlfriend replies. "Plus, I wanna try out to see if this body can do."
"Phew,... thank god." You relieve.
"Anyway, would you like to take this boy to the bed?"
At that moment, you take advantage of his relatively lightweight to pick him up and you then carry this naked little boy in the bed as he gasps and surprises at the same time. After you finally gently place him in your bed, your hands' cores hide his tiny body, so small and fragile. You easily pin the innocent looks of the little "boy" to the mattress, his slender arms unable to resist the strength of one of your hands while the other goes wherever you want. S/he can't stop you, and not that he wants you to stop, he seems to enjoy it. Even when you turn your girlfriend into a cute little boy, it feels weird to make out with him/her. But it doesn't matter. He's still the same girl you loved. Now once you're ready, you strip off all of your clothes naked as you begin to have sex with him and kiss him.
He moaned in seeming confused pleasure with your tongue thoroughly exploring his mouth. His hairless legs curled around your waist. A strand of saliva lingered as your lips parted from his panting mouth. His adorable face was flushed red and his eyes gazed half lidded up at you. Did he think you were done? Far from it.
Still pinning the little boy's arms above his head, you go to the nipple on his right nipple while your free hand plays with his left. To your surprise, your girlfriend/boy reacted far more to the nipple play than the tickling. Was he really that sensitive?
"Ah! Ah! Aaah! That feels...! Oh! Mmm... Oooh. Honey, slow down... I... I can't... Aah!" You do not slow down though. Nibbling, pinching, licking, flicking, circling, sucking... You play the moaning boy like an instrument until his quivering pleading becomes incomprehensible babble.
Sticking your fingers into his mouth and making him suckle on them, you use his saliva as lube as you begin to finger him, opening his hole one finger at a time. Now you were just far too turned on to second guess yourself. When he is finally ready, you let go of his pinned arms and use both hands to grip his hips. S/he's no longer trying to hold back, but just twitching and drooling as if you've already broken his mind.
A twinge of awareness returns to his eyes as the tip of your lubed-up cock finds the naked little boy quivering hole. "Honey..." the boy whimpers as you shove into him and he throws his head back and moans. One long passionate moan as you slowly push deeper and deeper and deeper into your transformed girlfriend.
Finally, all the way in, you look down at the gasping little boy beneath you. You can't believe how tiny his body is compared to yours. Yet you're inside him, or her? You just don't care anymore, all you need now is to fuck. You need to fuck so bad! You pound away, holding the boy by the hips and thrusting as fast as you can. He cries out, clutching the bedding like a life raft. He's so tight as the bedrock as if on a turbulent sea.
You raise his hips so his knees are next to his head and you pound him directly down into the bed from above.
"H... honey!" your girlfriend/10-year-old boy cries out after ten minutes of relentless fucking. "I... Think... I... Gonna... CUMMMMMM!!!!!" Sweat dripping from your chin, you pick up even more pace and time your orgasms to sink up. You fill the boy's ass as he lets out a stream of cum all over his face.
Panting, you lie down next to your girlfriend who is now a random 10-year-old boy, and take some tissues from the box as you wipe and clean his cum covered face and body. After you're done, you then hold and cuddle him like you did with your girlfriend after sex, even though, this little boy is your girlfriend that you turned her into by the suit. "So, honey..." he breaks the silence and looks at you. "What do you think about having sex with the little boy?"
At that moment, you look at his cute innocent face as he's talking to you. You then respond to him. "Well, it was weird, but kinky. I like it."
"Do you wanna try it again?" He asks.
"Maybe later, babe. Or maybe we can try something else." You then kiss him lips to lips as he enjoys it. You could get used to your girlfriend looking like this. Or you could change him back to your girlfriend or even alter him.