Yikes, your Majesty!
You ought to hear this:
http://wowseriousbusiness.ytmnd.com/ "you stole my Cloudsong" - not exactly a roleplaying game thing but very close. (I guess I should warn that this is a very harsh soundclip of a DAOC player going psycho over something that happened in-game).
Actually I never quite reached this point (I'm a 3, always have been), but I had a girlfriend who did, and it was quite awful. Right when Amber came out I had gotten us invited to an Amber Diceless game that was going on with some people I only knew slightly. So we showed up, and the game commenced. But at one point there was some kind of in-character confrontation, and apparently girlfriend (who had kind of a borderline personality to begin with) started getting really angry and nasty.. and it ended with her yelling and screaming at the hosts, and me trying to apologize my way out of the situaion. And us leaving.
That was the absolute worst situaion I have ever been in involving gaming. My reputation around the gaming store where I met these people was kinda ruined, and the story of the really out of control person who was a guest and acted like a total psycho became a kind of legend.