Online multiplayer games offer all sorts of social experiences and griefing is one of them. Griefing is when a player acts in a deliberately antisocial way, for example, shooting team mates, sending offensive messages to other players or going out of their way to make life difficult for new players. Griefing can range from an incidental nuisance to destructive bullying campaigns and around 25% of calls to online game complaint lines are about griefing.
So, are you a griefer or have you been griefed? Or both perhaps?
More about griefing in this Guardian article.