If I've told this story here before, feel free to skip over this.
A couple of years ago some friends and I went to New York City for vacation and one of the things we wanted to do was see a Broadway show. We didn't have a lot of money for tickets so we ended up in the very last row, and we were behind a group of high-school-aged kids (all wearing matching shirts from the same camp). That would have been fine, except in the row in front of us one girl jabbered to her friend for the ENTIRE show. The counselor at the end of the row (maybe 4 people down) didn't say a thing.
I think I had indicated to her to be quiet a couple of times (a look, a finger to lips, nothing impolite) but she completely ignored me. So (shocking my friends as I am usually easy-going) I got up and leaned over to her and told her politely but firmly that she needed to stop talking so the rest of us could hear the performance, or she should go to the lobby. She looked startled and said, "I was just telling my friend something," and I said, "You've been telling her something the whole show. Please be quiet." I believe she quieted down after that, but really, no counselor thought to tell her to behave? The counselors, to be fair, were probably college students, so not much older and apparently not really interested in discipline.
Sadly, I remember more about my encounter with this girl than the show itself.