I'm the most Kkkrackkkers of Amerikkkans so my tradition is just getting drunk off mulled wine and re-watching bad holiday movies with relatives I only kinda like.
I'm sometimes a little jealous of people who have weirder shit going on, like gremlins who slam doors and steal sausages or shitting Christmas logs. We need to bring back weird ass half-pagan shit.
In Sweden? I grew up with this in Finland, this tradition was alive in only a few villages in the archipelago here. I believe it still is too. Here it also used to be young men dressing up as these nuutti-goats before (which were up to no good unless you gave them food)), but has turned into this kids masquerade and going from house to house signing for treats. It was a lot of fun, there was a village dance after too where even adults were in costumes.