A Withering Glance guide to etiquette for concertgoers and theater patrons. That means you.

Don't

Laugh, snort or clap three times louder than anyone else in the audience. We get it: You like it. Now calm down.

Do

Take 15 minutes to select an outfit other than what you wear to mow the lawn. You are joining others for an evening at the theater or concert hall. No need to go all Cary Grant in "To Catch a Thief," but neither do we want to see your

Vikings T-shirt, cargo shorts and flip-flops. Do you really need that fanny pack at the Guthrie?

Don't

Take three minutes to "quietly" unwrap the crinkliest throat lozenge since the invention of the Life Saver. Just rip it open and be done with it.

Do

Learn how to silence your cell phone if it should accidentally ring during a performance. Most phones have an exterior button which, if hit once, turns off the ringer. So why do so many phones seem to ring four or five times before their owners discover this feature?

Don't

Smoke at the Xcel Energy Center, even if it is a Marilyn Manson concert and there's zero attempt at enforcement.

Don't

Kick the back of our seat. You may not have noticed, but we're sitting in it.

Don't

Allow your companion to snore loudly, a noise that really stands out during one of Osmo Vänskä's famed pianissimo passages at Orchestra Hall. Give him or her the sharp elbow.

Do

Arrive in good hygienic form. This doesn't mean spritzed up in more cologne than a low-rent hooker, but it does mean having showered in recent memory.

Don't

Ask us to move so you can sit together. We got here first.

Do

Hold your applause till the end of a symphony or concerto, as opposed to clapping madly at the end of the first movement. Do refrain from applause after a dancer has executed a double pirouette. Yes, it's pretty, but it's as routine to them as brushing your teeth is to you.

Don't

Text or Twitter. It may be silent, but it's bright and highly distracting, especially to us nosy neighbors.

Do

Talk back to certain movies. ("Fool! Of course he's behind that bathroom door.") It's funny, and who cares?

Don't

Talk to your companion at a movie. It's annoying, and we care.