Griefing is the activity of deliberately annoying other players in a game on the internet, or doing things that spoil the game for them. You get griefed; someone is griefing. Same world as griefer — informal, gaming only, a bit accusing. It is not a word for ordinary meanness at school or at work, and it is not the -ing form of feeling sad. The ordinary verb for sadness is grieve, not grief; griefing belongs to the game slang where grief itself became a verb. Though actually, many players just say grief as a verb: Stop griefing, or Don't grief us.

惡意搗亂（遊戲裡專門破壞別人體驗；常直接說 grief）