Instead of the pleasant and friendly holiday saying "Have a Merry Christmas", when you burn someone with a horrendously powerful insult finish them off with a "Yea Merry Dissmas pal".
The phrase is most effective when used during the holiday season.
Guy 2: I'd rather have an ugly Mom then one who blows homeless people for heroin.
Guy 1: (Crying because it's true**)
Guy 2: Yea, Merry Dissmas Pal
**The truth of the burn is not necessary, it just has to be an effective insult