I have a coworker who is really nice, but his mannerisms drive me up the wall! Some things he does at his desk (while I'm seated right next to him):
*Instead of clearing his throat as most people do, he does a loud, sharp cough. Several times a minute.
*Talking to himself.
*Tapping his head multiple times
*Putting his hands to his lips and exhaling in little short bursts.
Nice guy, but sometimes I just want to say enough already!
Another one: People who are so determined to play Devil's Advocate in every conversation that they will go to embarrassing, absurd lengths to prove you wrong. Worst example I can think of:
I was explaining to somehow how a man I tutored was very rude and abrupt, therefore aggravating to work with. So determined to prove me wrong that his rudeness was his own fault, she burst out defensively, ''Well, maybe he has autism!''
Keep in mind, she does not know this man at all and there was nothing to indicate that he had autism at all. I just found it ridiculous that she would bring that up just because she was so determined to be sure I couldn't be right.