When your bang'in a chick that's so wasted she won't be able to remember anything the next day.... finish yo business and don't forget to draw a large question mark on her forehead in permanent marker before you leave.
Random Stranger: Why do you have a Question Mark on your forehead?
Hungover Chick: I don't know. I don't remember anything from last night.
Random Stranger: Huh. You must have got fucked by The Riddler last night.