My daughter wants us to leave cookies for Santa. I'm going to leave them on a tray by the tree, uneaten, with a note that says,
You didn't label these for nut and gluten content, are you trying to kill me?
- Santa
Let's see ... You place a large red velvet bag full of wrapped gifts near the tree. Knock it over and have the packages spilling out. Scattering some blood around and having it tracked through the front door and onto the front lawn adds a bit of verisimilitude. Works better if you have a tiles entrance.
Then take that deer you shot a couple of nights ago and lay him out on the driveway. Put a red rubber nose on him with a cheap single-cell flashlight inside. Use discount store battery so it dims and dies out quickly in the cold. Make sure the nose is visible form the front porch. You might scatter a little blood around in the snow and place a few old leather belts and a couple bells around to look like the remains of a harness.
Then backing away from the body wearing your buddies over-sized rubber boots you go up on the porch where you drape a 'Santa hat' over the muzzle of your shotgun and fire a round into the woods to startle everyone. Drop the holed and still smoking hat a few feet inside the door. And then fire another round ten feet from the door so the smoke and noise gets everyone into the living room to see what happened.
You tell everyone you heard something and went to check it out with your trusty shotgun. Seeing a dirt bag dressed in red and white you shot him. Following him through the door as he bounded into a sleigh you fired at him and got one of his reindeer. Any luck at all you can time it so the kids are looking at the fallen deer when his light goes out. 'Oh, look ... Rudolph just died'...
You might want to keep some Thorazine on hand for when the kids go ballistic.
Follow by by making deer meat the centerpiece of every table. Consider having the head, with red rubber nose, mounted.
After a year of psychotherapy (at $110 every 50 minutes) to get over you 'shooting Santa', and another year or two getting over the idea that you're the sort of father who would stage such a thing, the kids will be fine.
As parents it is important to 'build memories' and establish family traditions. Merry Christmas.