I heard you're going out with my friend from school, but I know you have no clue what to do when it comes to sex. She'll spread the word that my brother is crappy in bed, and I can't have you and your inexperience ruining my school popularity. So, I decide to show you a thing or two to save my reputation - but there's rules. You can't tell anyone about this, and absolutely no touching (because I'm your sister and that's just weird). I do a sexy striptease and challenge your ability to keep your cool while you watch a naked girl. Then I want you to whip out your cock so I can teach you a few things. But when I see how big your cock is, I just can't resist....even if you are my brother. It's ok though, because you promised not to tell anyone.... right? It's our little secret