Yerfdog is a floating, inflatable dog that says "YERF!". He is the mascot of Hamumu. His picture can be found in the top left corner on this wiki. In Dr. Lunatic and Dr. Lunatic Supreme with Cheese Yerfdog primarily serves as the player's guide in the various tutorial hub level. He has no set life, cannot be damaged or killed, and any enemies and projectiles pass straight through him. When the player walks into Yerfdog, however, a special speech bubble may appear.