7 Days of Incest/Day 1/Forget the Music, Just Rub Against Her!
At this point you realize with how you had your sister pinned against the shelf, there wasn't an easy way for her to wiggle out from your grasp. Rose was stuck between a rock and a hard place... literally with that last part. Wrestling for control over the music gives you great opportunity and an excuse to rub up against her with every chance she goes for the on/off button, and that prospect is just too delicious to overlook. With that realization, you stop giving a fuck about the music and promptly shift your focus to getting some of your little sister's ass.
With your attention now redirected towards lust, you press against her body a bit more trying to rub that big ass of her's against your crotch, only to discover that she's just a bit too short for you. You will have to boost her up a bit if you wish to try and rub against her bootyful bounty (you silently grin at your own terrible pun).
Pushing up against Rose all this time has caused the lump in your pants to only grow harder. Even though you feel the built up pleasure increasing with every movement, you want more, and with the way you have her locked in your grasp there is no way she can escape. Taking a firm hold of her waist with both hands, you pull her up and press her behind firmly against your crotch. You eye her carefully, unsure if she was paying attention or not, but to your relief she still seems distracted by her lust for music. Assured of your momentary safety, you continue your work of resuming the task of quickly rubbing your bulge against her skirt-covered ass cheeks.
As if to taunt her, you make sure keep Rose just out of reach of the controls, causing her to make more sudden rapid movements that do little else but work to your purposes. But, almost unconsciously, it seemed as though Rose was returning the favor: With every movement made, her ass jiggled around your clothed dick, calling out and seemingly inviting you with its hypnotic gyrations as it sends waves upon waves of pleasure into your thick meaty shaft. Before long, every movement of your little sister seemed to join in that call, as though she does indeed know about your dirty and perverted desires for her. Like a little greek Siren, Rose's body itself seems to be asking, no begging, for your attention with her bouncing and jerking, promising you untold sexual wealth from the passages hidden between her legs. And who were you to resist those kinds of advances?
Keeping the bulk of Rose's weight held on your legs, you divert some of your attention to taking off your belt. As quietly as you can muster, you undo the buckle of the thick leather material, and slowly unthread it from around your waste, all while continuing the charade of preventing your sister from hitting the boombox's power button. Letting your belt slowly drop to the floor, you carefully and skillfully manage to undo your pants, letting your dick flop out and bounce lightly against Rose's skirt covered ass.
Rose shifts slightly in your grip as she feels the sensation of a thick object jab her in the backside, causing her to pause and glance over her shoulder with a questioning look. But with the way she is positioned against the bookshelf, and how close you two are to each other, all she can clearly see is your face. Shrugging off the feeling, she turns back around and once more tries to fight against your hold.
With her once again preoccupied with trying to get her way, you take the opportunity to once again grab ahold of her waist with one hand, and slip your dick under her skirt. As you do so, you catch a glimpse of what she's wearing under it.