Ouch. That’s the unavoidable reaction to this clip showing Conan O’Brien’s Friday mishap, in which he hit his head and had to be taken to the hospital for observation. O’Brien was filming a bit with Teri Hatcher in which he and the "Desperate Housewives" star square off in a mini-triathalton. O’Brien gets through most of the stunt safely… until the very last minute. Check out a preview below (and watch the full segment on Monday’s "Tonight Show").