We've started watching old movies on Sundays with our kids. Stuff like Mary Poppins, Wizard of Oz, and Disney classics. Our five-year-old can get nervous about some of the newer animated films (Mufasa! Nooooo!), but he's really enjoying a lot of our carefully-explained Sunday choices.
So a few weeks ago we watched The Princess Bride. And tonight, whenever I ask him to do something, he's been responding with "As you wish."