When someone is really tripping about something or said something really stupid.
Michael: Did you hear what Kevin said last night?
Kobe: Man, Kevin is always eating coal.
New variation of "fuck off" or "eat shit and die." Came up with this when I had trolls piss me off and it's Christmas time. So instead of telling someone to eat shit, you can tell them to eat coal.
Troll says: Hey Asian, go steal another white husband.
I say: Hey troll, I doubt anyone is getting your rude ass anything for Christmas. Go eat coal.