All underpants have to pass the truck test.

That test asks the question: If you got hit by a truck and they took you to the hospital and undressed you, would you want to be caught wearing those underpants?

Until very recently, as far as American men are concerned, only two kinds of underpants passed the truck test - boxer shorts and briefs of the variety that are white, floppy and waist-high, with a fly.

Curiously enough, both kinds are inherently ridiculous. Lots of clothes are inherently ridiculous. For instance, most shoes are ridiculous, especially women's high-heeled shoes - all women look like Minnie Mouse in them. And men . . . well, there used to be an all-night carry-out off Dupont Circle where the biggest transvestites in the world strode around in their size 15 stiletto heels, a memorable sight. Anyway, before we digress further.

Boxer-shorts advocates always felt their gear was more aristocratic, somehow, or at least more conservative. Boxers were the standard issue in the service. They were sold at Brooks Brothers. Wearers sometimes even defended their choice by citing data that said too much heat near the generative organs could cause sterility, hence the need for loose-fitting underpants.

Briefs fans cited that mysterious male need for "support," and felt, secretly, that boxer shorts were pretentious and old-fashioned.

Both sides felt that anything snug, low-cut and brightly colored should be worn only by bodybuilders of uncertain sexual preference. Or by foreigners.

LIke those French. Life magazine and the National Geographic used to run photos of Frenchmen diving off Jacques Cousteau's "Calypso" in these tiny little droopy wool bikini things that looked like mini-diapers. Their underwear was just as tiny. It made your flesh crawl to think about actually wearing that stuff. And worse, the women all thought it was sexy.

The black men broke the whole underpants game wide open. They started wearing sexy little paisley tricot briefs, mesh bikinis, even tie-dyed nylon briefs. Hip white guys found black clothing stores, or hip department stores where they could buy three pairs of underpants in a plastic tube of startlingly suggestive shape, underpants which cost $5, $6, $8 apiece. Apiece! They didn't wear them in the locker room, perhaps, but they wore them in the bedroom when they discovered that women, ah yes, dug them.

Consequently, the truck test has become so liberal that one wouldn't want to speculate on what men would be ashamed to wear anymore.