Leave the yuks to Shecky Greene: You're not as funny as you think you are. And you're not up there to prove you're a triple-threat (Director! Office drone! Raconteur!); you're there to shill for donations. If you don't have your own personal comedy writer or a proven flair for being funny, don't go for a laugh. When you don't get one, it'll throw you and make the rest of your time onstage even less comfortable for all of us. This rule also extends to wearing funny hats and doing impersonations.
Quit with the vibrator jokes, already: Cell phones are no longer newfangled, and neither is any clever line you might think up about "turning off anything that beeps, rings, or vibrates." Ditto the joke about unwrapping candies before the play commences. Those are polite chuckles you've been hearing in response to these now-more-tired-than-ever lines, and, in theater, a polite chuckle from the audience is the equivalent of a fart in a synagogue. It's bad enough you have to tell adults not to take phone calls during a live performance; trying to make it amusing just adds to our pain.
Keep your gams to yourself: One of my favorite local directors once appeared onstage to address an opening-night audience in a pair of sawed-off combat fatigues. Okay, so we were in a hip, supercasual black-box theater, about to watch one of those dark, pensive plays that critics used to refer to as "edgy." But I was so distracted by this fashion faux pas that I never heard a word of his possibly interesting speech. Maybe a pipe burst in his apartment this afternoon, I remember thinking, and all his clothes were ruined and he doesn't know anyone with the same waist size and couldn't borrow a pair of trousers. Or maybe he's replacing one of the actors in the play, and he's already in costume as a homeless war veteran. Nope. It turned out the guy was just a slob a fact that kept at least one of us from hearing a word of what he said.
Keep your hands in your pockets: I talk with my hands, which is annoying and makes me look stupid. But you won't find me giving curtain speeches anywhere, ever. Neither should you if you're afflicted with an inability to speak without also flapping your mitts at the audience. Trust me: We'll be so mesmerized by your pelican impersonation, we won't hear a word you're saying.
And finally: Don't discuss international politics or weep during a curtain speech. (Anyone who thinks I'm kidding didn't attend theater in the weeks immediately following the September 11 terrorist attacks.) Don't read from a script or from cue cards. And never, ever disparage people who refuse to support the arts. This is America, which means most of the people listening to you speak tonight were brought here by a loved one, have never bought a theater ticket in their lives, and would rather be home watching American Idol.