Tonight Show host Conan O'Brien was back on TV Monday night after suffering a concussion when he slipped on a slick floor while performing a stunt with Teri Hatcher, who had recently raced in the Malibu triathlon. "As many of you may know, on this past Friday's show I was doing a stunt and I hit my head and suffered a slight concussion," Conan said. "And I promise, if you're a good audience, I'll do it again tonight." Then he quipped: "For five seconds I actually understood the plot of Lost!" (Photo: WENN)