People who tailgate you when the next lane is clearly open are also fun. I once had someone speed up to me on a highway (I was going over the speed limit as it was), honk his horn for at least ten seconds, go around me, and do the same thing to the next few cars. If it was an emergency, it would've been faster to just go around everyone, which was definitely an option, so I don't know what that person's problem was.
I also once had someone swerve into my lane right behind me and honk at me for being there (I had just gotten my license, so I may have been going a little slowly, but again, the whole other lane was still open).