One of my pet peeves is people who are rude to everyone else and expect people to apologize to them for rudeness yet never make any kind of apologies of their own.

Sorry have to add another,
People who are so into their own little world and worried about themselves they will stop in the middle of the aisle of a store and not even move when people nicely say "excuse me" to try to get by or who wait for 5 minutes to try to buy something they are standing in front of. RUDE!!