What is the most annoying mannerism you see in people?

I don't know if this is really a mannerism, but my biggest pet peeve is when people talk to me while looking another direction. I've known several people who talk that way and it really makes me uncomfortable. They look when they listen, but away when they talk. I'm not sure if they even know they do this, not sure if they can help it or not, but it's hard for me to carry on a conversation with someone who isn't looking at me when they're speaking to me.

i may not be very popular for this but i generally get a little annoyed by most australians because they have this tendency for their tone to rise at the end of a sentence like it does when you ask a quaestion. I shall try and explain more clearly, when you ask a question your voice sort of rises at the end, thats how we know we are being asked a question. Aussies however do this at the end of every sentence so they will simply say something with no question in it but your never sure if they have actually asked a question or not. It can get very annoying

yes when someone is talking and they point at something but they point right close to your face I just want to bite their arm and say dont point so close to me. Or if someones say whatever.

I'm annoyed at people who spits just everywhere while drinking. Those who don't cover their mouths when sneezing and those who bites their fingernails. This are just simple behavior that I think they can stop but doesn't even care for it, that's the reason it anooys me.

I don't like it when someone sucks there teeth. It drives me absolutely mad. I don't usually say anything about it. But I find it incredibly irritating. My mothe does it alot and I had a friend when I was a teenager that always did it. I used to tell my friend all the time but she said she would just do it without thinking. She never stopped the whole time I knew her. It almost seemed like it would get worse the more she tried to stop.