Know what really irks me?

Some players may ignore you because they don't read english. As a matter of fact, a lot of alleged english-speakers right here in the good ol USA barely speak english, much less read it.

And BTW the fact that you don't take online chess seriously doesn't automatically apply to everyone else out there. Honest. Trust me on this one.

I suspect that most players, regardless of any language barrier, after a few hundred games of online chess will know what gg means. As for the taking online chess seriously, maybe they do, but they shouldn't. I most certainly don't think that anyone should take it seriously enough that they are rude in either a win or loss. There is no excuse for that, even if they have hurt feelings.

I think the only thing that really annoys me is when you have a really solid game playing as black, your opponent ekes out a win literally by one pawn through a forced promotion, and then he/she immediately starts talking smack, as though they completely destroyed you.  Bonus points if they then refuse a rematch.