Quote from Ted in P.S. I Love You
Ted: Look, there's a fine line between love and insanity. It's the Dobler-Dahmer theory.
[Lily and Barney groan]
Marshall: Damn, I always forget the little one.
Ted: If both people are into each other, a big romantic gesture works. Like Lloyd Dobler holding up the boom box outside Diane Court's window in Say Anything. But if one person isn't into the other, the same gesture comes off serial-killer crazy, or Dahmer.