What little things do you do to bug people?
One of my favourites is, when in a queue, to fail to progress in an orderly fashion. I like to let big gaps open up in front of me. I think it especially bugs SJs. The people behind you tend to crowd up on you in an attempt to force you to go forward, even when there are a number of people still in front of you and there is no chance someone is going to avail themselves of the extra space to cut in.
I also quite like, when conversing with a fastidiously neat person, to glance repeatedly at their forehead.