theatre ettiquette

Mind your theater manners
Theater is not the place for free-form dialogue of any kind, but for some reason, theatergoing couples seem to believe that when they giggle and coo or offer running commentary on a performance, their love alone must create some sort of soundproof force field akin to a hyperbaric chamber. Sorry, lovebirds, but everyone around you hears your every amorous word.
(via Scrubbles)

In a similar cell-phone centric article, bad theatre behaviour is looked at in a wider social context, the old shortened attention span and the newer plague: fear of commitment.
Aside from the growing lack of attention span in this country, there is another equally appalling trend. These are the people who can't seem to derive enjoyment from anything they see. I'm convinced they do this because they don't feel they can afford to give part of themselves to the event at hand. I think that's another negative result of the Internet and TV culture. These days, people are used to being able to walk away from what they are viewing, and so are unable to fully invest themselves in it. Because of the fact that people are becoming less and less accustomed to being involved in anything, a certain amount of fear ensues.
Theatre Etiquette Gone but Not Forgotten

I know that the MTC program note warns patrons about the decibel range of a cough both muffled and unmuffled, which might be enough to add fear of coughing to the ennui of Net-head fear of commitment.
Meanwhile Perth's Black Swan Theatre company has a nice take on the don't list:
It is nice to clap! Feel free to stand up at the end of the show, clapping wildly and calling ‘bravo, bravo’. This is good and will make you very popular with the actors"

and adds a list of folkloric practices never observed by boynton.