'70s sitcoms weren't always content to simply make audiences laugh. Some writers pushed into increasingly serious territory, taking advantage of the creative room they were given. "We were allowed as much latitude as we could envision," "M*A*S*H" creator Larry Gelbart told The Atlanta Constitution. And while some darkness was baked into "M*A*S*H" because of its wartime premise, other moments on this list come from shows with a much more lighthearted reputation. '70s viewers tuned into these five episodes expecting to laugh, only to instead be left in tears.