People who can't drive themselves; by this I mean those drivers who, on their way to passing you (or vise verse) pull in behind you and stay there.
One day going to work (6am Sunday no traffic) a woman gets on behind me, speeds up until she is less than a car off my bumper and stays there for the next 10miles, I exit the x-way as she continues to tailgate me. After speeding up/slowing down several times she refused to move, now it's been almost 20miles of no traffic 4 lane road and she's still so close she could count my hair follicles so I checked my brakes (better to be safe right?).
Now she passes me like I did something wrong.
Drive yourself or eat my bumper!!!
PS. to have fun with these types while in the Porsche, on the exchange ramps I go as fast as possible and watch them as they struggle to keep from hitting the wall.