when his friends are round they like to put the ball in the stick and chuck it repeatedly against the wall. A lacrosse ball is heavy, so it makes quite a big noise.
Another flatmate has this thing on his keys where you whistle and it beeps (so he can find them). My flatmates often spend about half an hour whistling at it so they can hear it beep.
I swear they have the brain capacity of neanderthals.
What do annoying people do to annoy you?