Nothing
When uttered by a female it means "I'm gonna see how many times you ask and beg for an answer...then I might tell you..maybe."
Guy: "What's wrong?" Girl: "Nothing." Guy: "There has to be something..." Girl: "No, really, I'm fine." Guy: "Okay suit yourself." Result: Poor guy's sleeping on the couch that night. Shoulda forced the answer out of her. Sucks, but true.
By Kamel Jocky