Biff: "I figure I'd cut you a break and give you the honor of going with the best looking guy in school."
Lorraine: "Yeah, well, I'm busy."
Biff: "Yeah, doin' what?"
Lorraine: "Washing my hair."
Biff: "Oh, that's about as funny as a screen door on a battleship."
Marty: "Screen door on a submarine, you dork."