Keith Olbermann returned to the "Late Show" on Tuesday to deliver David Letterman's patented Top Ten List. The topic? "Reasons To Watch The New 'Countdown With Keith Olbermann,'" appropriately. Olbermann delivered the zingers with gusto, even the slightly disturbing top reason.
It's Olbermann's second appearance on Letterman's show in recent months; in May, he chose the show to make his first television appearance since leaving NBC.WATCH: