Your sister is a little sneaky. She thinks you can't see her playing with herself. You decide to pull your dick out and let her use it. She looks around to make sure no-one can see. Shhh don't tell anybody ! mmmmm your sister moans on your Big Cock. Mmmm brother, will mom find out? you bust big Loads on her ass and tell her mom will NEVER find out. but in the back of your mind you know this is something you will always have over her..