The little boy's lie is just a little one--he tells his parents he didn't eat the cookies--but still (in the form of a big fat green monster) it hangs about bothering him, even though he insults it and tells it to scram. This goes on. . . and on. . . until, fed up with the thing that is now sitting on top of him, the boy finally exorcises the lie in the only way possible--by 'fessing up. Good psychology, cleverly attired, but that's all.