What's the weirdest family tradition either side of your family celebrates?

My dad’s side has an ugly Hawaiian t-shirt party on occasion, but not annually. It started when an uncle of mine was broke and out of a job, and Christmas was approaching. By Christmas eve, everyone was opening one present each when the uncle that I do not remember the name of because there are 6 on that side of the family comes in the front door with Wal-Mart bags full of Hawaiian t-shirts and then randomly throws a single bag at each family member. A few years afterwards, when my uncle was in better financial stability, someone had the inspiration to throw an ugly Hawaiian t-shirt party. Simply enough, the ugliest shirt won a bowling trophy with a man wearing – guess what? – another ugly Hawaiian t-shirt.

What’s your weird family tradition, annual or not?