The Mari Lwyd is often depicted with a horse skull attached to a pole, a white cloak, and a mane made of colorful streamers, holly, or ivy. The skull may have lights or baubles for eyes, and a spring-fixed lower jaw that snaps shut. He wants to be let in your house to drink all of your alcohol and raid your pantry. Might be coerced with other means. You have to "rap battle" him till he leaves or bargain with him.