I get annoyed by this:
1. Talking to someone who is constantly looking at themselves in any available reflection. It peeves me off to no end. Seriously, if you have something in your teeth; excuse yourself, fix it, and get on with the conversation. If you’re just looking at yourself because you like what you see and you find yourself so distracting that you can’t look away while we’re having a “conversation”, I’m going to walk away and leave you talking to yourself. I’m sure you both will have so much to talk about anyway.
2. Talking to someone who texts while talking. This is also not okay. Gentle Reader, this Miss Manners is pissed off at your inability to treat the people in front of you with enough decency to look them in the face when they’re talking to you.