Stupid Human Tricks, Natalie Portman, X-ecutioners, Xzhibit, Biohazard Late Show with David Letterman : Season 9 Episode 153

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.