1. Turn Off Your Cell Phone
 Somehow the most obvious rule of good theatre etiquette is still the most often disregarded. Turn it off, people. Turn. It. Off. And, no, putting your cell phone on vibrate isn't good enough - the people next to you can hear that weird buzzing sound, too.
2. Don't Send Text Messages During the Show
You may think you're being all incognito, but in a darkened theater, the light from your cell phone screen is incredibly distracting to those around you. And why do you still have your phone on anyway? We just told you to turn it off!
3. Eat Your Dinner Before the Show, Not DURING It
This isn't the movies. Munching on candy and chips during a live Broadway performance is annoying to your neighbors. Bringing hamburgers and buckets of KFC (oh, yes, we've seen people do it) is an outrage. If you're absolutely starving (after all, nobody wants to hear your stomach growling either), then a little quiet snacking on something fairly unobtrusive like M&Ms is acceptable. But it's still better if you avoid eating altogether during the show and get your treats in the lobby during the intermission instead.
4. If You Have To Cough, Cover Your Mouth
In this age of diseases-of-the-week from SARS to swine flu, there is nothing more bone-chilling to a theatergoer than the sound of a nearby cough and an accompanying gust of air. Yuck. Coughing is inevitable, but failure to cover your mouth is unforgivable, so try to keep Kleenex or a handkerchief on hand. And if you have a cold, be sure to bring some lozenges with you.
5. Unwrap Cough Drops and Candies in Advance
If you anticipate any coughing fits during the show, be sure to unwrap your lozenges before the performance starts and have them at the ready. That crinkling sound is like nails on a chalkboard during a show. And, no, unwrapping it S-L-O-W-L-Y does not help the situation ... it's much, much worse.
6. Don't Be A Disruptive Miss Manners
Sure, it's irritating when someone's cell phone goes off, but what's even worse is when the brief breach of theatre etiquette is followed by a series of overreactions from other audience members. Annoyed "Tsks," "Hmphs," hisses, snarls, and shouts of "Turn it off!" along with scandalized glares can be just as distracting as the original disruption.
7.Don't Talk During the Show
A quick whisper to your neighbor, or an audible reaction to something interesting that happens on stage is fine (this is the live theater, not the morgue), but keep conversations to the intermission and after the show. Nobody needs to hear your theories on what the next plot twist will be, and please refrain from asking your companion to explain to you what was just said onstage. By the time he or she explains it to you, you'll have both missed something else important.
8. Don't Sing Along
It's tempting sometimes, we know. But if you want to sing on Broadway, then you're gonna have to audition like those people up onstage did. Your fellow show goers paid the big bucks to see the kids performan, not you. Save your sweet singing for post-show karaoke. 
9. Don't Feel Like You Have to Dress Up
Although opening night audiences usually dress up a bit, there is no dress code. Technically you can come in shorts and flip flops, but we advise against this, especially since theaters usually crank up the air conditioning. Dress nice of don't do the suit and tiw thing.
10. Try Not To Fall Asleep
If the show is truly horrendously boring, then your snoring may be taken as a protest of sorts, but generally it's just disruptive to those around you. It's also insulting to the hard-working performers up onstage. Note to the young people: do not be tempted to wake up the old people mid-scene as they often make gurgling noises as the come to their senses, wait for a song or intermission.
11. Standing Ovations and Entrance Applause Are Overdone - Don't Give Into Peer Pressure
Traditionally, polite applause for performers at the end of their performance is appreciated. Standing ovations are for the end of a show. Lately these reactions seem to have become obligatory, and unfortunately when standing ovations and entrance applause are done out of mere habit, they essentially become meaningless. Ultimately, how you react is up to you, but let your true feelings guide you on this.
12. Respect the Space and Comfort of Those Around You
The average theater seats make Economy Class on a commercial airliner look luxurious, so sometimes a little elbow bumping can't be helped. But you can practice good Broadway etiquette by taking care to not lean into your neighbor, hog armrests, intrude on other people's already limited leg room, or let your big heavy coat hang so far off the back of your seat that it ends up in someone else's lap.
13. Come Clean
A day of busy Palm Springs sightseeing in the summer or a post-work / pre-theater session at the gym can leave you sweaty and not-so-sweet smelling. For the sake of those sitting next to you, try to make time for a shower before arriving at the theater. And don't go too heavy on the aftershave or cologne afterwards - too much of a good smell can be just as bad as unpleasant body odor.
14. Stop Whooping
Your enthusiasm for the show is wonderful, but should be tempered out of consideration for both the audience and the performers. Nobody needs to hear people shrieking, whooping, screaming, and hollering. It is theatre performance, not a rock concert, not an arena or a sports stadium. If you are so moved to react to the show, then a gentle clap after the song is appropriate, but whooping is not. Save your whooping for the final curtain call, where you can whoop as much as you would like. Woop, woop!
15. No Photos At Any Time
No photos are allowed in our theatre, so please do not attempt to take them. We do not care if they are for your facebook page or or for twitter as no-one really cares (except your mom, maybe). Taking photos in the theatre lobby is sometimes allowed, but the ushers can be really mean about it*. Forget trying to impress the ushers with "who you know", or "who you are", as there is a famous story about when the ushers told George Lucas (of Star Wars fame) to stop taking photos before the show started. After this frosty reception, do not expect to see Star Wars The Musical anytime soon.

* Ms Stephanie and Mr Richard