But then Letterman discovered that the Straight Talker wasn't on a plane being whisked back to D.C. to save the nation. Instead, he was elsewhere in CBS's NY studio, being made up for an interview with Katie Couric. So Letterman included on his show a live feed of McCain in the make-up room, exposing the big lie.
Now that's funny.
UPDATE: Here's the video--it's a bit long, but quite funny, and pretty biting.