People who stand around having a chat in the middle of the supermarket aisle with their shopping trolleys blocking the way.
Shopping trolleys left in car spaces.
Toilet seats left up and people (in my household!) that don't replace the empty toilet paper roll.
People eating noisily.
People with colds constantly sniffing - BLOW YOUR NOSE PLEASE.
Hmmm..there's more but I don't want people thinking I'm a cranky cow haha