Quietly unzip your pants and penetrate Kara right there
From Create Your Own Story
With Adam so engrossed in trying to beat his sister and Kara sitting snug in your lap with your fully-hardened cock hotdogging her wiggling ass, you figure now's as good a time as any to make your move. You quietly slide your hands down to your lap, unbuttoning and unzipping your fly, then wiggling your hips until your pants fall down enough to let your monster cock free. You then slide your hands up to Kara's waist, first giving her a squeeze before hooking your thumbs into the elastic of her shorts and panties and easing both of them down at once.
You almost expect Kara to make some sort of noise in protest, but the only reaction you can gauge from the teen is a slight smirk appearing in the corner of her mouth and her butt wiggling in your lap to help you ease down her clothes. You watch as her supple, peach-colored ass comes into view, then her pink pussy, her nether regions rosy red and glistening with her obvious arousal. You steady her hips with one hand and aim your shaft with the other, pressing the head of your hard-on against the entrance to Kara's wet sex and gently guiding her hips back into your lap. You resist the urge to moan as the tight teen pussy sinks down onto your member; she's much tighter than any of the girls you've had before. Likely, you realize, she is a virgin. You can't believe your luck that she's letting you take her innocence like this, so informal, so fucking sexy.
Kara allows your cock to slide all the way into her tight pussy, her silky wet tunnel squeezing tight around your shaft as it penetrates her fully. She's being quite controlled in spite of having such a huge dick in her formerly virgin cunt, the girl still focusing on her game while you ease her up and down on your member, enjoying the feeling of her pussy sliding back and forth over your sensitive shaft. It's like heaven, better than any girl you've been with, and made even hotter by the fact that her brother, your best friend, is sitting right next to the two of you while you fuck his little sister.