1) Eating. Anything. There's nothing worse than watching and listening to someone chomp and slurp over food during a chess game. And yes, the crumbs and grease get on the board and pieces.
2) "Adjusting" my pieces. This only happened once. I told him never touch my pieces again. I don't care what the rule book says.
3) Hitting the clock on his time because he doesn't realize I've already moved and thought he forgot to hit it when he finished his last move. Terrifically annoying and has happened more than once.
4) Not resigning in lost, soon to be mated positions because their chess coach told them "never resign." Their chess coach was wrong. Resign.
TMB
Anybody else come across Chess.com's "404 missing page." I don't know about you, but if I was in an OTB tournament, I would go nuts watching Hikaru swirling that pawn. Curious if anybody else has the same problem?