My biggest pet peeve is that many people don't understand 4-Way stops.

It's especially annoying when riding a bike. I know the rules and I follow them. Don't stop to let me go. Do your job. I'll do mine.

Oh wait. Don't take a left turn that blocks traffic! If you have a line behind you and no opening in sight, bite the bullet and go straight. It will take you an extra minute, but save several fellow drivers several minutes - each.