Jerry Seinfeld returned to his stand-up roots last night on CBS's Late Show with David Letterman and joked about, well, nothing. "Everyone says you don't do the show anymore, what do you do?" said Seinfeld, whose Late Show appearance marked his first TV stand-up performance in nearly three years. "I'll tell you what I do. Nothing." Seinfeld went on to admit that doing nothing is hard work. "You have to be careful. The idea of doing anything can easily lead to something that would stop me from doing nothing, and that would force me to drop everything." The funnyman also touched on such hot topics as fatherhood, mad cow disease and Subway spokesperson Jared. Despite Seinfeld's much-hyped stopover, Wednesday night's Late Show was clobbered in the ratings by NBC's Tonight Show with Jay Leno, besting the toothy Letterman and co. by 42 percent in the metered markets. In Seinfeld's hometown, New York, Tonight outdelivered a fourth place Letterman by a whopping 117 percent. Don't quit your day job, Jerry. (Oh wait...)