1) Learn how to use quotes. How did you possibly not notice that you "quoted" my entire post by reposting it yourself?
2) Urban Dictionary? Wow, that's pathetic. Have you seriously not been gaming long enough to know what "griefing" means? Anyone who needs to confer with Urban Dictionary to figure out what a griefer is shouldn't be calling themselves one to begin with.
How about you try that thing called Google and find a real definition, to educate yourself so you don't look like such a dumbass. Maybe try a reputable site like Wikipedia, not a joke site like Urban Dictionary where almost 100% of the entries are satirical tongue-in-cheek exaggerations.
If there were too many big words there, you can use this site to decipher their meaning: http://www.dictionary.com/
Probably their 'victims' are half to blame for this. They complain about 'griefing' after getting killed twice and that just encourages them further.
"YEEEEES. GRIEFER! I am the sower of discontent, I am the ravager of hope, I am the sworn enemy of truth and justice. A digital super-villain without equal! Hahaha."
Lmfao, that would explain it. You get a handful of people together who don't know basic gaming terminology, give them all guns, and the half that get killed manage to convince the half that killed them that they are griefers.
"What, I made someone else mad?! I AM GRIEFER EXTRAORDINAIRE!"
In which case, beating the other team in a deathmatch makes you a griefer, winning a race makes you a griefer, running away when someone starts shooting at you makes you a griefer, and basically every other way of playing the game normally. I'd be surprised if someone could find a way to play this game (or any game, really) in which they play with other people but never manage to agitate anyone else.
You'd think it'd be obvious that simply being an asshole doesn't qualify you as a griefer, but I guess common sense shouldn't be taken for granted.