While you were out filling your body with the kind of mood-altering chemicals that could lead to a tragic drivers license suspension of your own on Friday night, David Letterman was luring recently rehabilitated probation-violator Paris Hilton into a Late Show ambush, promising Hilton a chance to promote her latest brand-extension efforts (another perfume and a straight-to-video acting credit—oh yeah, and some, like, charity thing or whatever) to a national audience of eager consumers.