Your sister notices you leaving your friends alone and entering the bedroom. She follows you but she has other plans. She is wearing a top with her nipples visible and that gave you a boner. She wants to help you get rid of it but a handjob doesn't work, so she uses her mouth till you cum inside. She wants to return to your friends but you want to fuck her. She gives in but it needs to be quick, someone knocked on the door but she made an excuse so they dont enter, you cum inside your sister!!!!