Jolly Lumpus

"I am jolly, for I am the Lumpus which destroyed all the other Lumpi on my way to becoming the top nightmare creator in the world"

The jolly lumpus is belived to be immune to every germ in existence, and has gained sapience. The only way this nightmare can die if it gets slaughtered, cut, bashed, blown up, or slashed 50 times or so as it has thick, fireproof, skin which is also a strong base.