What other hat ideas do you have?
Before committing to this tradition, I did a quick Google Image search for "goofy Christmas hats." There are a surprising number of them. Big Christmas trees, elf hats with big ears. mistletoe dangling on a stick, reindeer antlers, and even a giant chimney with Santa feet sticking out. I'm thinking we'll have enough options until she stops believing in Santa. Then if I feel like being really evil, I'll bribe her to continue the tradition with expensive toys and gadgets. And if I can get her to do it until her 21st birthday, there's this option:
Crossing my fingers.