I saw 300 in theaters twice. The first time, it was a semi decent theater, and had a pretty good experience. The second time, the theater was crap, and there were a bunch of kids in the movie who must have been about 14 or something. I am pretty sure they bought tickets to a different movie, because they didn't have any adults with them. Anyway, they would yell at the movie and make rude comments very loudly. I was pretty ticked already because the video and audio sucked, so about half way through I stood up in the middle of the movie and yelled over to them to "Please be quiet" in a rather rude tone of voice. Heck, there were only 30 to 50 people in the 200 person theater anyway, so I didn't even care if I embarresed my self... But it was worth it to get those dumb kids to shut up. My buddy appreciated it, as it was his first time to see the movie.
So, next time some people are acting up at a theater, let them know they can shut up or get out! *laugh* Really, why bother going to get some other high school kid working at the theater to complain about the noise when it might be his friends, anyway.
Yes, you CAN do something useful about it!