cancel someone's Christmas

A darkly colourful idiomatic expression meaning to kill, destroy, or completely finish someone off — as in ending them so thoroughly there's no Christmas in their future. It's used with a blend of menace and dark humour, more theatrical than literal in most contexts. You'll hear it in crime dramas, action films, hip-hop lyrics, and street slang when someone wants to sound threatening without just saying 'kill'. The phrase lands somewhere between a mob threat and a punchline.

(slang, idiomatic) To kill or destroy someone.