A male or female who appears to one as attractive, until they get to know the person and become disappointed to find out they have absolutely no personality.
Girl 1: How are things with Will?
Girl 2: Ah, I'm so disappointed. He seemed perfect, but every date with him feels like forever because he's so dull.
Girl 1: Haha, he sounds like a total doorknob. You'd better ditch him.
Guy 1: Dude, look at that girl over there. Pretty hot, right?
Guy 2: Oh, Stacy? We used to date, but then I realized she was a total doorknob. Nothing to her. She can barely hold a two minute conversation.