Boing

Boing is one of the 'failed' experiments created by Mojo Jojo for the purpose of being the ultimate 'Powerpuff-Deestroying' being. He was considered a failure, despite his incredible shapeshifting abilities, due him being, as Mojo Jojo puts it, "A complete idiot". As such, Mojo Jojo left him on an uninhabited Planet, where he now just joyfully bounces all around the place to his heart's content.