A phrase often used to back pedal after you said something insulting, especially to a friend.
Girl 1: What happened to your face?? It looks like you got in a fight with a raccoon...
Girl 2: Huh?? You don't like my make up?!?
Girl 1: I'm kidding!!
Girl 1: Your boyfriends a manwhore. I slept with him last night. He wasn't all that good either.
Girl 2: But we promised we would wait til marriage!! *bursts into tears*
Girl 1: Umm...I'm kidding?
Girl 2: Oh okay!