Beeping in traffic
If you're sitting in your car and there are cars in front of you generally it means that they have cars in front of them and so on. It is therefore completely pointless to sit in your car beeping your horn!
Who are you trying to move? The car in front who has a car in front of him? Sit down, put some music on and shut the fuck up with the beeping, it's pointless and it pissed me off!