Writing in The Stage, Mark Shenton gave this example of audience behavior in the theater:
"An audience member at Sunny Afternoon last week told the London Evening Standard how he was "left fuming" when an usher asked him to stop humming along to the show. He genuinely couldn't believe why he was creating a disturbance: "I just find it so bizarre to explain why I was singing at a musical. You pay a lot of money... All I remember is my foot tapping along to the music and humming along. Suddenly I was told, ‘Can you quieten down?’ If it was a drama then yes but if it’s a musical you expect to be allowed to sing along to some of the songs that you remember from your youth.”
I share this man's outrage--when I was at the ballet some of the people sitting near me had the temerity to take exception when I did an interpretive dance in my seat.
Shenton also relates stories of people in the audience texting, taking photos, and even taking calls during performances.
That's in addition to the older custom of people chatting away during performances, as though they were sitting on their sofa at home. One time when I turned around and asked the people behind me to quiet down, one of them gasped, "How rude!"
Still, that was a mild response compared to one time when a friend and I politely asked a group of people at a movie in Los Angeles to be quiet. They said they'd see us in the parking lot after the movie. It was only when one of the more brightly-lit scenes illuminated the audience that we realized they were gang members. We left early.
I think we need to wire theater seats and give talkers and texters and hummers a few thousand volts. There could be some fatalities, but it would be worth it.