Tonight Show host Conan O'Brien certainly isn't afraid to generate "laughs at his expense," said Lynn Elber in the Associated Press. On his show Monday, O'Brien played "cringe-worthy" footage of his skit-gone-wrong last Friday when, while racing with guest Teri Hatcher, the 6-foot-4 comedian slipped onstage and hit his head, causing a concussion (watch

). The "audience gasped" at the footage, in which "O'Brien looked like a rag doll," but he and his sidekick Andy Richter were quick to joke about it.

Conan O'Brien may have been "joking sardonically on Monday night about the head injury he sustained," said Dave Itzkoff in The New York Times, "but the footage of the incident is more frightening than laugh-out-loud funny." The injury was so serious that O'Brien was "unable to complete Friday's show" and had to be taken to the hospital.

O'Brien didn't even know what year it was after the accident, said Gina Serpe in E! Online, and it even "briefly rendered O'Brien's otherwise razor-sharp verbal abilities slurred and the entire incident, in his mind, blurred." Or, as O'Brien put it, he hit his head so hard that 'for five seconds, I understood the plot of Lost.' Now that's hard."