https://derpibooru.org/1016785?scope=scpef121a3ad3892112e197b723d6570dbf499fbd5ff
>You and your big sister Gilda finish up a game of basketball.
>Or rather, she just finished playing basketball while you ran around trying to get the ball out of her hand.
>.....or rather RATHER, she just finished playing basketball while you tried not to think about all the times she'd grab and hold you against her sweaty body while she snatches the ball out of your hands.
>Did you know what your sister doesn't wear a bra when she plays with you?
>You do now.
>Did you know that she has nipples like thimbles?
>Boy howdy, you do now.
>You normally HATE basketball, but Gilda insists on trying to keep you in shape.
>"I can't keep beating up punks who pick on you forever, you dweeb. I'm graduating this year and then you'll be on your own."
>You're just heading on inside when Gilda pulls you aside.
>"Hey, littlest brother!"
"ONLY brother" you correct her
>"Whatever. Get your ass up here, I need you to do something for me."
>You fall in step beside her.
"Like what?"
>This earns you a glare.
>"Like, whatever I want you to do."
>For some reason this makes her blush a bit.
>The two of you head upstairs and your sister unexpectedly pulls you into the bathroom.
"Hey! What are you-"
>Your sister's hand clamps down over your mouth and she levels a mighty glare at you.
>"Keep it down, idiot. Mom and Dad won't be home for a few hours and we need to wash up so that you can do whatever shit mom left for us."
>...then why are you here?
>You struggle to pry your sister's fingers off of your face.
"Sure thing, Gilda. Give me a shout when you're done, okay?"
>The grin she wears makes you feel uneasy.
>"I don't think so, little man. It's time you repay me for all those times I stood up for you."
>What?!
>You thought she was doing all that to be a good sister!
>Dammit, dad was right; there's no such thing as a free lunch.
"What do you mean?" you ask, resisting the urge to take a step back towards the door, "What do you want me to do?"
>"Stay right there," orders Gilda, turning around and fiddling with the knobs on the bathtub, "I'll pummel you if you move an inch."
>Well, shit.
>Hot, steamy water pours out of the faucet and into the bathtub, which your sister has plugged up.
>"I hope you're ready, Anon," she says, not even turning around to speak to you, "because your job is to help clean me up."
>What?!
"What?!"
>She slams the knobs to the off position and stomps over to you.
>When she's close enough, she punches you in the shoulder and clamps another hand over you mouth again.
>"What did I just say?!" she hissed, "Keep your mouth shut!"
>After a rather intense staring contest, Gilda lets you go and goes back over to the bathtub to start things up again.
>When the water is about 2/3s full, she turns everything off and motions for you to come over, which you do reluctantly.
>You REALLY don't like the gleam in her eyes.
>"First things first, dweeb: get these clothes off of me."
>You open your mouth to shout again, but a glare cuts you off.
>"I fucked up and put on old clothes this morning, and they're all to small."
>She motions to her breasts, which are straining against her cotton top.
>Your heart leaps into your throat when you realize that some water from the bath must have splashed up onto her chest; the material is nearly transparent.
>Her dark nipples are very clearly visible.
>After you've gotten a nice look-see, she waves a hand at her shorts.
>They're struggling to contain her hips and the lips in between them.
>They've ridden up her ass and are producing an AMAZING cameltoe for your viewing pleasure.
>Something small-ish and round pulses right at the top of her pussy lips.
>You realize with a jolt that you're looking at her clit.
>It has to be the size of your thumb!
>"Oi!" 
>Gilda roughly slaps your arm.
>"Eyes up here, buck-o. Now, c'mon!"
>Your sister tugs at the bottom of her shirt, which seems to be almost fused with her skin.
>"Help your big sister out of this DAMN top already!"

"Y-you can't be serious, Gilda."
>She just CAN'T be.
>The way she glares at you and shoves her chest into your face begs to differ.
>"Get. Going." she growls.
>Fuck it.
>You're going to get your ass beat by your sister for falling for a joke that has been taken so unbelievably far, but you swear to God that you're going to get a handful of tiddies out of the dead before you do.
>You grip the bottom of her shirt and try lift it up over her tits.
>As you expected, the material sticks from all the sweat and water.
>"Idiot," she growls, "Don't you think I tried that? Do something to loosen it up."
"Like what?"
>"I don't know! Get creative!"
>You try to shimmy the cloth back and forth to loosen it up, making your sister's tits swing back and forth.
>The cotton unsticks a bit and slides around on her slicked skin.
>Gilda grunts when the material brushes against her diamond-hard nipples.
>You flinch and stop tugging on her shirt when she grabs onto your shoulder, but she just squeezes it.
>You look up at her and find that her eyes are closed and her face is bright red.
>Said eyes flutter open and she gives you a shove with the hand she had on your shoulder.
>"Why did you stop, you scrub?"
>Gilda tries to tug the shirt up over her head again but the cloth barely budges.
>"Does it LOOK like I can take this fuckin' thing off of me? Get back to work!"
>You grab her shirt again and try again, working in tugs to your previous shimmying.
>With the sound of a vacuum-sealed jar popping open, the top unsticks her skin all at once and flies up to her face.
>You're left with a big faceful of warm, wet tits.
>You don't even care that they're your sister's any more.
>You think it's about time you got that handful of tits before your sister beats you up.
>Feeling happier than you have in a long time, you plant your open palm over each fist-sized nipple and give Gilda's chest a good squeeze.
>Your sister gasps and cuts back a moan when you give her a good squeeze.
>Gilda's breasts are soft and have the perfect amount of give.
>Her nipples press against the palm of your hand as you rub and grope her milk-bags.
>"H-hey, stop that!" she moans, making no attempt to stop you, "You aren't s-supposed to-ohhh!"
>With one hand, you caress the smooth skin of her breast, weighing her fat tit in your hand and loving the way it sinks into the soft flesh.
>With your other, you pinch the dark nipple and give her teat a bit of a twisting.
>Without warning, your vision shifts from a pair of breasts to the tiled floor of your bathroom.
>A dull pain blooms in your jaw, and you poke your tongue around your mouth to make sure that you don't taste any blood.
>You look over to your sister, who's standing over you with her fists clenched and a harsh glare on her face.
>"You little shit!"
>Gilda reaches down and grabs both of your hands, pulling you upright.
"S-sorry," you groan, hoping that she won't hit you again.
>Instead of hitting you, Gilda guides your hands to her waistband.
>"You've earned yourself some overtime, dweeb."
>Her hands are unexpectedly soft, and they hold your own with unexpected care.
>If you didn't know any better, you'd swear you were holding hands with your sister.
>The moment is over, however, when she shoves your hands down the front of her shorts.
>"No funny business this time, Anon," she growls, staring you in the eye as though daring you to try something.
>Your first few tries pulling her shorts over those wide birthing hips of hers are unsuccessful, resulting only in your fingers slipping out of the waistband.
>You need to go deeper.
>You grab the waistband with one hand and tug the front open.
>You glance up at your sister to see her reaction to you pulling her shorts open like that, but you're met with the sight of Gilda biting her bottom lip and gazing at you with half-lidded eyes.
>Hesitantly, you guide your other hand down the now-open shorts.
>Your fingers sift through your sister's pubes as you reach down as deep as you can go so that you can get as much leverage as possible.
>The heat and humidity on your fingers is growing the further down you go.
>"Aaah!"
>Your fingers bump something fleshy and round.
>D-d-dweeb, wh-what did I just s-say?!" moans your sister, biting her finger.
"Sorry, Gilda! I'm trying to-"
>"Shut up." she says, breathlessly, panting.
>You explore around your sister's crotch for a little bit, finally getting to feel those fat, meaty pussy lips you saw through her shorts.
>Gilda leans against the wall while you rub her pussy, squeaking every time you give her grape-sized clit attention.
>Her moans fill the room, and it's music to your ears.
>"An-nawn~" she gasps, weekly pawing at your arm, "S-stop it... G-get these fuuuuhuhuhuuuucking~ short off al-already!"
>You stick a finger into her well-lubricated slit and she absolutely SHRIEKS.
>"C'mon~"
>Gilda's powerful thighs clamp tight around your hand as a powerful orgasm tears through her body.
>She wraps her arms around you and tugs you to her chest while she shivers and groans.
>After a long couple of seconds, your big sister slides down the wall, taking you with her.
>"Y-you..." she gasps, breathing hard, "You little cr-creep..."
>She tries to glare at you but it softens.
>Gilda pulls you against her bare chest again and rests her chin on top of your head.
>You can hear her heart racing with your head surrounded by breasts.
>"You still gotta clean me up, dweeb."
>A smirk plays on your lips.
"Fair enough."

And then they fucked in the bathtub.
The end.