Your girlfriend was riding your dick when your sister waltzed into your room like she owned the place. Talk about a cock block. Your girlfriend was so mad she left without even letting you finish. Of course your sister thinks it’s the funniest thing in the world, and now she’s making fun of you, in your own bed, while you lay there with a hard dick and blue balls. You’ve never really seen your sister in a sexual way before, but now that you’re dick is hard and horny, you can’t help but notice her tits… and she’s actually pretty cute. She’s never really thought about you that way before either, but after seeing you fuck your girlfriend… she admits that it was kinda hot… if you weren’t her brother… maybe she’d fuck you. But you are her brother… and she’s your sister… and you definitely shouldn’t fuck. Right?