These lantern slides on silent movie theatre etiquette from the 1910s show that inconsiderate audience members have existed since the dawn of cinema.
Most early movie theaters had only one projector so “etiquette slides” were used to divert the audience while reels were being changed. These glass slides often featured lighthearted instructions for proper behavior while viewing a film.
They're collected in Silent Movies: The Birth of Film and the Triumph of Movie Culture.
I don't get this one - what else would you use?
From Old Hollywood, via Boing Boing.