Hot Summer Job/Force your sister upstairs
"Nope. You can't back out of a dare sis." You step forward from the couch and guide your sister to her feet by her arms. "So move it!"
Immediately your sis gets all pouty. She just stands there, arms crossed, looking up at you doe-eyed. A few seconds of that is as much as you can stand. You crouch down, shoulder her waist, and hoist her into the air in a sort of fireman's carry.
"Hey! Big meanie!" she shouts, giggling as you both approach the stairs.
"What? I'm helping!"
Your hand grips the back of her thigh, just under her skirt. As you bound up the stairs you allow it to drift higher, nestling innocently against the underside of her small but well defined little bubble butt. Her legs are so slender, which is part of the reason her butt is so accentuated. She's always been small, like she needs a growth spurt that just never came. You doubt she's even 60 pounds yet but her well proportioned body just makes her a late bloomer. After entering her room you slip the cute bundle of a sister off of your shoulder and drop her onto her bed.
"There. At least you're in your room. Which means now you can take your clothes off."
"No way!" she protests, bouncing up onto her butt. "Not while you're in here! That's against the rules!"
Hmm. Not where you were going with this, but that could be fun. "Yeah, says the girl who tried to get out of what she agreed to."
"No I didn't," she says guiltily, glancing at the floor. Since she was the one to bring this up with you it was clearly at the front of her mind ever since coming home from school.
"Sure, sure, you 'forgot' your dare. Anyway, now I have to be in here. How else will I know you've followed through?"
"I can throw my clothes into the hall like yesterday!" she quickly suggests.
"Oh yeah, 'cuz there aren't any clothes in here," you scoff, gesturing around her unkempt room. "Enough stalling. Time to strip, sis."
Bree grins, leaning back on her bed. "Make me."
That sure sounds like an invitation.
You stare each other down, each waiting for the other to move first. Her grin creeps up her cheeks. Your left eyebrow rises. The moment you bend forward your sis squeals and tries to scramble away. You snatch her ankle first, then grab a fistful of skirt. She kicks her feet, already giggling up a storm. The unprotected skin beneath her short skirt flashes at you in pale frenetic bursts. Since her ankle isn't your target, you switch fully to her skirt and pull up with both hands. You lift most of her body into the air and after a couple more seconds of squirming Bree worms herself right out of her skirt, her compact bum just squeezing its way past the garment's waistband.
The skirt is quickly tossed aside while you watch your sister roll into a sitting position on her knees. Seeing her aggressively posture up wearing nothing from the waist down is far too welcome a sight. This is your kid sister after all. That isn't stopping her though. Her feet are kicked out to either side, her hands outstretched defensively, waiting for you to attack again. She's baring her teeth and you half expect her to roar like a cub, although that might just be a naughty smile she's sharing.
You do attack as expected, latching onto her hands. Your fingers interlock with hers, trying to be as sporting as possible. Bree grunts and shifts her weight, trying to out muscle you. Of course that isn't going to happen. You start to push her down, slowly and steadily, then decide to switch things up. You let her push against you until her arms are fully extended. Then, pulling back hard, you yank her off of her bed.
"EEEEEE!!!"
With an assisted landing, she finds the floor gracefully on the tips of her toes, still latched onto your hands. You shake one of your hands free and immediately shoot for the hem of her shirt. You get it up to her chest before she reacts, dropping to her heels and releasing your other hand in order to rescue her rising top. Hands grab and shove in every direction as you each try to gain the upper hand. Unable to make progress, you secure her wrists and stretch her upward again lifting her off the floor for another brief moment. Bree stares up at you panting, the stupidest smile on her face. Carefully, you transfer both of her wrists into one hand, making sure to keep her on the tips of her toes. Either you finally get a good grip or she decides to let you win, but one way or another you are able to peel her shirt off of her trim little frame without much more in the way of resistance. With a release of her wrists and dropping of her arms, her top is fully stripped away. You take a step back, throwing the uninteresting article toward her closet.
"Are you happy now?" asks a pink-faced Bree, her hands meeting in front of her crotch. She's practically prancing from foot to foot, naked and amped up from your little strip-fight.
"Yeah, I suppose I am," you answer truthfully, unable to keep yourself from staring.
"Well you must not be, else you would've left already!"