Planet Piss is the long-awaited side project of Dethklok bassist William Murderface. Planet Piss is first mentioned by Murderface after a disappointing birthday party in which the rest of the members of Dethklok performed for him a pessimistic birthday song about dying (known as "Birthday Dethday"), Jean-Pierre baked for him a mercury-frosted birthday cake which he disliked upon first sight, Dr. Rockzo made him a guitar-shaped balloon, and he got nothing as a birthday present.