Ah Bartleby! [1]
In Herman Melville's classic story "Bartleby, the Scrivener: A Story of Wall Street" [3] (1853), the character of the eponymous scrivener repeatedly says, "I would prefer not to," in response to requests at the law firm where he works. Take it a step further: Come up with a signature response of your own and try writing a short story in which it is the only sentence one of your characters ever utters. See where it takes you.