8x96 - Late Show with David Letterman

For the last month or so, a little old man walks onstage during the monologue, stands next to Dave, and walks away. Tonight, there's a twist: the old guy walks out, and followed soon after by an annoyed-looking Calvert. Both walk off stage without incident. Also, during Mailbag, "Police Chief" Bill DeLace gives dating tips, while "Bill Clinton" (Gerard) steals one of the guest chairs.