When to stop smiling

You just finished talking with a classmate in the library. You smile. Maybe it was a funny subject or perhaps you were smiling so that he would think you got the joke.

For whatever reason (see below), your cheeks crinkle up, your lips pull back so severely that your top lip threatens your nasal cavity and your natural dentures peak through the gap.

You've probably been holding this awkward pose for several seconds. Your psyche has clicked into red carpet mode and you are stuck.

You turn away from your friend to attend class and accidentally make eye contact with a pretty young woman who looks up from her studies at the wrong time.

You are still smiling even though the conversation that triggered your expression has ended.

She looks behind herself self-consciously, confirming in her mind that your grin is directed at her. And by the time she turns back around, you have straightened your features. But that's when she smiles back and the whole encounter repeats itself with you turning around.

It's awkward.

This exact scenario literally almost happened to me. I made up the fact that the woman was pretty and a few key details. But to draw a lesson from "I, Rigoberta Menchú," inaccuracies mustn't keep us from learning lessons.

The smile is, of course, a defensive expression. It is like brandishing a shield in conversation. When someone insults you terribly -- say, refers to your mother as a poorly bred monkey with gingivitis -- you smile. Your expression protects you from harsh words and allows you a moment to recover before responding (it takes a second to "unsmile," especially if you are Nancy Pelosi or John Edwards, for whom the act of grinning requires several minutes of warmup and stretching). If a hoodlum holds you up, the IRS calls or you misplace your shoes in someone's fridge, the textbook reaction is to smile.

When you fail to timely remove the grin, it's like walking down main street porting a buckler on your arm. Everyone will wonder why you have a hand-to-hand combat defense tool and will want one of their own. If they have one handy, they will remove it to demonstrate preparedness.

That's why the woman at the library smiled back. Seeing that I was armed with a toothy grin, she returned the expression and showed that she was similarly equipped.

Yes lady, you do have teeth.

But you (reader, not lady) do not want to cause smiling arms races. They are wastes of people's cheek energy and can threaten those without good smiles.

How would you feel if the entire village were having a buckler parade and you had gotten rid of yours in a garage sale? Pretty miserable, I'll wager: Everyone takes to the streets in a display of shield firepower and you have to loiter defenselessly.

And you are conspicuously absent. (Conversation in street. Bystander with buckler (BWB)1: "Where's reader?" BWB2: "I don't know, he sold me this sweet buckler, though!")

Those who think they have bad smiles often return grins with blank stares or threatening looks. They feel threatened by your smile. They know that you are a better defensive conversationalist because they see your gleaming pearly whites.

If you threaten enough with your grin, people will take counter measures. They may work on their own smile -- visit an orthodontist, invest in whitening creams or schedule an appointment with a plastic surgeon (the modern day blacksmith).

Or they may go on the offensive and try to ruin your smile. Many barnyard tools will accomplish this; shovels, hoes, pitchforks and sledgehammers will all do a number on your smile.

Dentists and orthodontists benefit whether your friends choose the defensive (whitening) or offensive (shovel) approach. But you might have a preference.

I don't mean to scare you. But I think you should at least consider the dangers the next time you smile at a stranger. Or the next time you smile at a farmer. Or the next time he smiles back.