I’ve also really enjoyed this thread…I’ve heard all sorts of things whispered and even screeched during concerts so this is not a new revelation but a very sad one. Even when etiquette rules are posted blatantly in a program there’s still one or two idiots who will ignore them and do whatever they please….
There’s a relatively new dine-in movie theater in my town and one of the ads at the beginning of a movie shows the scene from “Gremlins” where the theater blows up at the end with all the Gremlins inside. At the end of that clip the screen reads something like “No talking during the movie or we’ll take you out.” It follows with “…and texting totally counts as talking.” It finishes with a screen that informs you that if someone complains about your party you’ll get one warning…after that you’ll be asked to leave with no refund. It’s the kind of theater where you write your food order on a ticket and leave it standing on your table so it can be easily grabbed by a waiter/waitress. It’s easier to complain about people because they don’t know if you’re ordering food or making a complaint. I’ve had to complain twice about people in a movie and both times I was not the only person to complain and they were asked to leave. Maybe that’s what we need for classical concerts, operas, plays!