*sigh*
I honestly would expect that kind of behavior nowadays at popular shows such as Spelling Bee, RENT, Wicked, etc. However, there is no excuse for it.
I went to see All Shook Up with my drama class last year, and our teacher stressed theatre etiquette every day for a week leading up to it. He gave us guidelines for proper dress and explained how going to see a show worked (many kids in the class had never been to Broadway shows, surprisingly). He also warned us that he would pull anyone who was being disruptive out into the lobby for the rest of the performance. During the show, we actually behaved very well.
Maybe it's because I'm a regular theatre-goer, but I can't imagine doing anything like that. It's completely disrespectful and ridiculously immature. I'd be embarassed if were to ever be a part of a disruptive group.
"A little rebellion, now and then, is a good thing." - Thomas Jefferson