I have a massive hatred for people who fidget or worse, tap their fingers during a conversation. It screams "hurry up, my time is too valuable to listen to you" and it immediately makes me second-guess everything I say in fear that they'll cut me off.

The worst was a guy who had a very loud clock in his office...and tapped his fingers in time to its ticking. To this day, I'm not sure how I managed not to throw that fucking clock through the window.