We had some terrible Christmases when I was a child - divorced parents, nobody got along, my mother was a crap cook and had a violent temper and my stepfather had Victorian tendencies (no talking at the table) so Christmas dinner was generally horrendous on a number of levels. This wasn't improved during the years when my dad was around for Christmas, because we'd get dropped off at his (freezing, uninhabitable) house straight after dinner, where he'd have bought enough meat and cheese to feed an army and expect us to eat it all. Christmases at home tended to end with a blazing row and someone storming out in the middle of dinner/charades/the night.
I love Christmas now (and am NC with my mother) but at around this time of year I do get the slight collywobbles remembering how awful it used to be. I have this horrible but funny image of my mother's face under a gaily coloured paper hat snarling "you've ruined Christmas for everyone, now shut your mouth or I'll knock your block off"
So what's your "worst Christmas dinner ever" story?