The one person that you want to kill, but can't because you would miss them to much. Especially, when they embarrass you or mess with stuff to piss you off. Kinda like family but worse. You can get rid of family, but not your best friend.
Fred: "Dude, did you just get us lost on purpose?"
Fred: "You better be glad that you are my best friend, or I would kill you!"
Tod: "Sure you would."
Fred: "My foot is about to meet your face!"