‘Bathos is a tradition from the dignified or grand to commonplace or laughable; an anticlimax […].' The term was first used in this sense by Alexander Pope in his treatise Peri Bathous; or, The Art of Sinking in Poetry (1728).
From the Ancient Greek βάθος meaning ‘depth’, bathos is generally a sudden change of tone in a work of writing, usually from the sublime to the ridiculous. When used unintentionally or executed poorly, this may result in sappiness. When used properly, this may create a comedic effect.
Bridgekeeper: Stop. Who would cross the Bridge of Death must answer me these questions three, ere the other side he see.
Sir Lancelot: Ask me the questions, bridgekeeper. I am not afraid.
Bridgekeeper: What… is your name?
Sir Lancelot: My name is Sir Lancelot of Camelot.
Bridgekeeper: What… is your quest?
Sir Lancelot: To seek the Holy Grail.
Bridgekeeper: What… is your favourite colour?
Sir Lancelot: Blue.
Bridgekeeper: Go on. Off you go.
Sir Lancelot: Oh, thank you. Thank you very much.
– Monty Python and the Holy Grail (1975)
 Fiske, Robert Hartwell (1 November 2011). Robert Hartwell Fiske’s Dictionary of Unendurable English: A Compendium of Mistakes in Grammar, Usage, and Spelling with commentary on lexicographers and linguists. Scribner. p. 71