Dave shows footage from rehearsal of Kenny McGowan tripping over the ""Will It Float"" tank; Biff visits the Indianapolis Motor Speedway for the Indy 500 time trials; a participant in tonight's ""Stupid Human Tricks"" that can maneuver a tennis racquet all over his body flirts with Natalie Portman in the green room.
click here to see where to watch or .
Ready to Watch Late Show with David Letterman, Season 9, Episode 153?