Online? Leaning towards yes (dammit, I voted without thinking it through). I'm normally a nice guy, but quiet IRL. In game, I can talk more, but not by much. It's also fun trolling trolls since they can't piss me off easily (and get everyone else to join in the fun till they give up).
Karma meter RPG's don't matter much. I can play good or evil easily. Up till recently, I didn't know that people actually struggled to bring themselves to be bad (my one friend was the sole exception, and I didn't understand it)