The Demon of Insincerity is one of the Demons of Ignorance from the book and movie The Phantom Tollbooth. He tricks Milo, Tock, and the Humbug into a hole. He then boasts about how scary he is until Milo finds out what he truly is.
"I'M THE LONG-NOSED, GREEN-EYED, CURLY-HAIRED, WIDE-MOUTHED, BONE-LEGGED, BIG FOOTED. AND IF I DO SAY SO MYSELF, I'M ONE OF THE MOST DREADED THINGS IN THE WHOLE WIDE WILDERNESS"