In honor of the anniversary of the first-ever sitcom broadcast on a U.S. television network (fun fact: it was "Mary Kay and Johnny" back in November 1947), we're revisiting "Sitcom Deaths and Disappearances." Characters on sitcoms aren't supposed to die. So when they do, it's never less than weird. Mo examines some of the most infamous sitcom deaths and disappearances with Henry Winkler, Sandy Duncan and Alan Sepinwall.