Everyone has bad habits, but some seem to irritate people more than others.
Tell us one of yours, and one of the ones you can't stand.
For me, I constantly bite my nails or my lip. It irritates a lot of my friends and family, but I have never been able to stop - even with the horrible tasting nail stuff.
I absolutely hate people who constantly use their phone. The amount of times I've met a friend for lunch/dinner and they've been sitting there, chatting away to someone else while I'm sitting in front of them. Grr!
So, what are yours?