What Grinds My Gears More Than Anything Else
Bragging after winning a 5v4. Doesn't matter if it's my team that won, or if I was the unfortunate 4 man - it's just such bad sportsmanship. News flash: If you are one of those "gg ez" or "Haha you suck, outplayed" after winning against a team down a member - no one is impressed or thinks you're good. They just think it's sad that you're so happy about that win.
And it's usually always the person who was like 0/4/0 in lane phase who's the loudest in all chat when the game is turned due to the afk (because the person who actually carried the 5 man is usually apologetic about the game and his teammates)
I don't know, maybe this isn't everybody's tic. But it sure is mine XD