Cupp and Sean Hannity didn't accept Letterman's explanation of his joke, in which he regretted the comments, and slammed the lack of outrage in the mainstream media about the jokes in which Letterman referred to Palin's "slutty-flight-attendant look" and quipped that her daughter got "knocked up by [NY Yankee] Alex Rodriguez"

Cupp, who is a contributor to the Washington Post...