Late Show with David Letterman

In a bizarre running gag, Bill Cosby pretends to be so senile that a substitute cue-card boy introduces all of tonight's guests; Hilton Ruiz, Spaceman Paterson, Steve Berrios, and Andy Gonzales all sit in lieu of a temporary depleted band tonight (only Paul, Sid and Bruce bothered to show up); Sofia Vergara promotes Chasing Papi; the D4 performs ""Get Loose.""