This week's writing prompt comes from the Poets & Writers website. They too offer a great prompt each week, so there's really no excuse not to get writing:
In Herman Melville's classic story "Bartleby, the Scrivener: A Story of Wall Street" (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.