"The Other Sister"

Your girlfriend's sister has asked to stay over. She's had an argument with her boyfriend and needs to cool off. It's just you and your girlfriend's sister at the moment and as you're checking up on Demi, you notice her pajama top hasn't been buttoned up properly. You're not quite sure how to tell her that her tit is on show, but be honest, it's turning you on, isn't it?...