The year is 1983. At 8pm sharp on 28 February, 106 million viewers tune in to watch the M*A*S*H finale. The next day, everyone from truck drivers to corporate attorneys had the same reference points. For years, M*A*S*H functioned as a national ritual, allowing families across the country to laugh at the same jokes and debate the same plot twists. Of course, it wasn’t just M*A*S*H. Everyone could assume that nearly everyone else had seen shows like Seinfeld or Dallas.