He he, this is a topic that I have too many examples to list. I'll just list a few of the more recent.
-Company of Heroes while playing with a certain family member online. I'm far from the best CoH player out there, but I'm not horrible. My uncle has the game too, and loves the look and feel of the game, he just can't play worth a snot. Yet, he insists on playing only 2v2 online matches. I get enraged to no end at some of the plain dumb decisions he makes in that game. Its not the mistakes themselves that make me angry, its just that he insists on making them every. single. time. twenty games straight, against all advice from myself and even the enemy players.
-MGO. I just plain can't stand that game, but two of my best friends love it and keep insisting that I play. So I try....try so very hard...and suck worse at it than any other game I've played. Yet I just keep forcing myself to play despite getting angrier as I continue. It makes me mad because I'm fairly good with most first person and third person shooters, yet everything about this game feels 'off' to some degree (I would go into detail, but thats probably not necessary right now). Broke a controller and some drywall over it.
-Playing Counterstrike for more than an hour a month.
To be honest, lately I have been trying to stay as far away from competitive online gaming as I possible can. I just don't taking losing, badly, very well. =(