You know what really chaps my ass? WAITING.
Specifically, waiting for friends who have said they would like to meet me for dinner, but aren't quite sure when they'll be around. "5:30 or 6", he says. Then "running a little late." Just got an "on my way" text and it will be at least another half hour.
Sure-fire way to tell me you don't respect me is to waste my time.