You walk into Mike's room to find him frowning over the underwear scattered all over the floor of his room. Sure enough, it's all sorts of tight lycra briefs and more than a few jocks. You pick up one pair, a mesh jock which looks like the pouch has been stretched, and take a look at it. It's definitely stained with what's probably pre-cum. Now that's your pre-cum it's stained with. You chuckle as you start picking up the scattered articles.
"Got you pretty good there, didn't I, Mike?"
But Mike isn't looking at you, you just barely catch him looking at your crotch as you squat to pick up more pairs of underwear. Your bulge is obscenely visible with your pants stretched tight in the position you're in. You're following his gaze and staring at yourself, now, making your foot long cock throb under the two layers of fabric. You're excited to see the new you, but you suspect that Mike is even more eager.
"Whatever, I-I'm going to go get my stuff out of your room." Mike stammers and walks off. This is unbelievable, Mike is definitely gay for you and is practically walking with a limp from his little five incher going hard watching you! Since the swap, you've been thinking about girls, but you can remember what it was like to be gay. You remember lusting after Mike's perfect body, his big pecs, his full lips, that trim waist, those big feet, and that tight ass. You're so horny that just thinking about Mike's body is getting you excited, and a when you're this horny, a hole's a hole, right?
Plus, Mike is (or was?) the big stud on campus. Just the idea of making a man like that your bitch is making your balls boil. You take the dirty underwear back to your room just in time to find Mike going through your hamper, so you throw 'your' sexy new underwear in the corner.
"Dude I can't believe you even took my dirty underwear and threw it in your hamper! That's not cool!"
"Maybe I just knew you would know where to look for it." You respond with a wicked grin. Mike whirls around, face already red. He clutches his clothes, dirty and clean, to his chest and runs out of the room. But you're not done yet, you follow him. He's already fishing your clean undies out of his top drawer, and hands them to you without looking you in the eye. He's still taller than you, but wearing his cleats (well, your cleats, now) and walking around with your new fat dick leading the way, you definitely feel like the big man.
"Thanks, roomie. Speaking of 'roomie,' you sure you don't want to try one of these on? Make sure it's not yours? Looks like it'll fit you through the waist, at least..." Mike blushes even more.
"They're yours. Good prank. Ha ha." He says mirthlessly. On your way out, you notice something, a small strip of black cloth hanging out from under Mike's mattress. Oh, this is too good to be true! Mike is adjusting himself when you turn back around, drop what you're carrying, and close his door. He pulls his hands away from his crotch, then when he notices you glancing at the mattress, his ears burn.
"Mikey, what's this?" You say, walking over to lift up the mattress, revealing one of your dirty black jocks, hastily stashed underneath. "This is mine, isn't it?"
"G-gross dude, I c-can't believe you put one of your--"
"Save it, Mike." You feel the testosterone bubbling up inside you and Mike obeys your command. It is such a turn-on to see big-man-on-campus Mike so shy around you. "You decided to put this one away for later, huh? Sniff it while you jerk that little dick of yours?" Mike can't speak as you walk forward. "I've seen the way you look at me, Mike, and I think I could make you useful."
"Wh-what do you mean?"
"Get on your knees." You practically whisper it, standing chest to chest with the man whose feet and package you stole. The big jock trembles and sinks to his knees, like he's in a trance. "Smell me." But you don't wait for him to comply, grabbing his head and pushing him into your package, he lets out a muffled gasp. "Yeah, that's the stuff. That's what you want, isn't it?" You don't even know where this is coming from, it's like your sex drive has just taken over. "Go on, fish it out. Let's take a look at that big python you've been thinking about."
Still trembling, Mike unzips your pants reverently. "You're... y-you're wearing a pair of my underwear?" He squeaks.
"If you suck me good, you can keep this dirty pair instead, how about that?" His eyes get wide and he pulls out your cock, long and hard, twelve inches and fat. You're already leaking pre as he puts a football-strong hand around your shaft. Like he's giving in to his deepest fantasies, he takes you into his mouth, warm tongue lathing the head of that fat prick. "That's right, this is what you wanted. This is why you're always away from the dorm room, isn't it? Afraid you'll give yourself away if you see this bad boy swinging around. Yeah, suck my dick. C'mon, speak."
"Oh my god you're so huge." He breathes against your glistening head. You reward his obvious enthusiasm by putting the toe of your cleat into his own much smaller package, letting him rut against those big shoes he was wearing just yesterday. He's rutting like he's going to come, just from having your prick in his mouth.
"You're going to be my bitch from now on, Mikey."