Symbolism, Imagery, Allegory
We mention in the "Characters" section that Nicholas is a kind of godlike figure in the story. When Absolon declares "my soule bitake I unto Sathanas" after he accidentally kisses Allison's butt (642), he raises the possibility of an allegorical interpretation of the climax of the story, in which he plays Satan and Nicholas plays God. In this interpretation, Absolon's confrontation with Nicholas (represented by his branding of Nicholas with the hot poker) is an allegory of the enmity between God and Satan. It causes the fall of man when Nicholas's cry of "Water!" prompts John to fall from the roof. In a somewhat separate, but still Biblical allegory, you can even interpret Nicholas's fart "as greet as it had been a thonder-dent" and cry of "Water!" as an allegory of the flood that God sends to Noah many years after the fall of man.