Interrogation

When the girls come through the door, you're already right on the verge of cumming. The three girls stand shaded by the yellow-gold light of the upstairs chandelier behind them, and the first thing you hear is a torrent of shrill, tittering laughter. Your face is a mask of anguish as you lock eyes with each of them in turn; Penny’s hazel beauties with shallow wrinkles at their corners where she’s smiling; Christie’s baby blues shrouded beneath her full, dark eyelashes; your sister’s expression muted, but her pupils are strangely, suspiciously dilated, the almost-green of her irises catching the spare glow of your still-active computer screen. That’s bad enough, but then the moment passes and their gazes leave your face and rove in unison down your shoulders and lower back, drawn as if by laser-target onto your hopelessly exposed tushie. “Oh my goooood” moans Christie. “Look at his arse, I mean just look at it!”
“Mmm…” Penny bites her lip. “You could sleep on it.”
“Could feed yourself for a week on it!”
“Christie!”
“What? We were all thinking it!”
“Don’t you dare include me in this, he’s still—“
“Still your brother,” Christie rolls her eyes. “Yes, we know! But I mean like let’s be honest, this whole idea of yours wasn’t exactly normal. It’s fine to admit it was a little bit pervy on your part…” She trails off, raising her eyebrows expectantly. Your sister resists the urge to smirk. “I’m not a perv or anything, but…” For a long moment she just stares longingly at your bottom, swaying back and forth on the spot without another word. “So, how does it feel, stud?” asks Penny. “Back here again, caught touching yourself to just about the silliest porn I think I’ve ever seen.” Between everything—the way she says it, the look on her pretty face, the giggling of your sister and Christie next to her, the frozen frame of the video where you paused it, the fact that you’re naked and your stiff wet cock is dripping like a faucet between your hands as they stand there laughing at you—you do feel absolutely ridiculous. When you turn briefly back to the screen, another rolling wave of shame comes over you. The shot you’ve paused on shows the poor, humiliated cheerleader from behind, the pleated blue skirt still caught in the updraft of the vent, her knickers centre-frame and sandwiched sweetly between her tight, heart-shaped buttocks. “Why do you like this stuff?” Penny’s voice is soft and low and frighteningly close in your ear, and you can’t help but jump when her arms slide around your waist and she brings her hands down over your own. "It's so... chaste." She interlaces her fingers with yours, and when you look down, you see that she's working your slick, warm juices over them, as if going through the motions of washing her hands. "I mean, all this mess..." You flinch as she reaches down to the end of your cock, plants a thumb either side of it and rolls your foreskin gently back. You whimper pathetically, and in response Penny touches the tip of her nose to your neck as she continues tending to you, sliding your pre-cum up and down the length of your shaft and rubbing it over your twitching pink tip. "Over a cute girl and her underpants..." Her touch is maddening, you can scarcely even breathe as she carries on fondling. "My question is... is it the cute girl that does it for you?" Penny leans in to nibble at your earlobe, and her next words come out in a whisper. "...Or the underpants?"
"I... I... don't... it's private..."
"These are privates," she says, giving your shaft a lovely little jerk even as she transfers a small helping of the sticky stuff to your balls. "Your porn habits are right out in the open, no point trying to hide it now. We all know you like your babes bare and... blushing"
"I—I just... I like what I like," you say, defensively, struggling to resist the urge to let your eyes roll backwards into your head. "Everybody w-watches porn, everybody's got their t-thing!"
"True, but usually their thing is reverse cowgirl, or foot stuff, or..." She thrusts playfully forward into your backside, the material of her skirt playing pleasantly over the bare, curving skin of your cheeks. "Anal. But with your thing... I mean you don't even need them to be naked, do you? Your thing..." Penny takes her hands off your crotch, ducks under your arm and moves up to stand in front of the computer, manipulating the mousepad with her cum-smeared fingers to open up your history. "Was this your thing?" she asks, squinting to read the name of one of the videos you've previously pleasured yourself to. "Shy College Babe Loses Bikini Bottoms At Beach? Or Schoolteacher Wedgied By Jealous Mum? Or maybe Cute Cosplayer's Costume Falls Apart In Middle of Horny Nerd Convention?" You don't answer, your only reply is a shamefaced glare. Having those sensations, that intimacy taken away at the last second has you feeling well and truly blue-balled. Penny looks at you over her shoulder, her freckled cheek framed beautifully by her bright red curls. "Christie, I think he's still a little self-conscious; maybe you should show him just how much you like his tushy?"
"Show me... ?" You're absolutely baffled, and you only barely have enough time to turn your own head before Christie's shadow falls over you. All you see is gold; her hair, her skin... that, and the bright red colour of her lipstick. "Christ, I was starting to think you'd never ask," she says, her face bright with excitement and lust. "What are you... ? How are you going to show m—"

Your breath is taken away as Christie drops abruptly to her knees, clutches each of your pretty white buttocks and plants a passionate, lingering kiss on one. Her lips are all heat and wetness on the naked skin, and she creates a kind of subtle suction with them as she rolls them back and forth over it. That, and the sound of them smacking softly together gets you, and it gets you good. Warmth washes over both sets of your cheeks, and a fresh wave of pre-cum dribbles out you. Out of pure instinct, you try to envelope your shiny, glazed-over willy in your palms. You can't help it, but you're so hard and so thoroughly worked-up now that it's actually starting to ache. "Well, you wanna tell me about the Shy College Babe?" Penny reiterates, sweetly. "Or can Christie start giving your booty a little bit of tongue?" Behind you, you feel something narrow and equally wet peek shyly out from between Christie's lips. You think she licks your butt cheek with it, and despite your involuntary shudder, you worry a part of you might just like it.