Finally, a crack in your armor.Whistling will drive me up the wall pretty quickly too. My dad is the type of person that will just randomly start whistling all the freaking time while he's doing random things and if I'm around him I have to leave the room before I go through the ceiling.
I'd have to say overused brakes. Cars coming to stop just make that pure sound straight from hell. It's just about my greatest pet peeve.