Well, Felix, in the You Ess of Ayy, it's a celebration of the European invasion of North America and the theft of Native land. In Canada, it can be traced back to an early European explorer in the late 1500s who was just really happy that his ship didn't tear apart while exploring the waters around Baffin Island, and is now a day celebrating the fact we get to eat a whole damn turkey and not feel bad about it.