Region of origin: Wales
A local wassailing tradition in southern Wales, the Mari Lwyd (represented by a hobby horse made from a horse’s skull or crafted simulacrum) is led in a procession of revelers around a town at dusk during Christmastime festivities, knocking on doors and engaging the residents in a musical debate to be allowed inside and cause a ruckus. The exact etymology of the tradition is unclear but the Christmas connection may have developed as a combination of “mari” being homophonous with the Virgin Mary, and “Mari Lwyd” literally translating as “grey mare.”
Edit to add: Found this video on the Mari Lwyd tradition as it’s performed today.
Originally posted on Tumblr on December 14, 2015