8. Letterman Goes Off on John McCain (September 24, 2008)
Not someone who tends toward political comedy (he's a registered independent), Dave took the gloves off when Republican presidential hopeful John McCain bailed on the Late Show at the last minute, citing the need to return to Washington to focus on the mushrooming financial crisis. But when Letterman discovered that the candidate was instead prepping for an interview with CBS Evening News, the host ripped into him. "He doesn't seem to be racing to the airport," Letterman noted wryly, watching the live feed of McCain getting prepped to talk to anchor Katie Couric. What followed was a nicely surly smack-down: "This is not the way a tested hero behaves," Letterman said of McCain. "Somebody's putting something in his Metamucil."