WE'VE ALL HEARD THE STORY, ALTHOUGH THE NAMES, countries and languages change. It goes something like this: A well-intentioned traveler visiting an alien land asks a native a simple question, such as "Where is the post office?" But something is off -- the slightest tone, the merest inflection, a single syllable is out of kilter. And the earnest visitor, it turns out, insults his host, who hears instead "Your mother looks like red ants have been eating her face."

So it is with teen slang. Nuance is everything. Consider, for example, mess up versus mess 'em up. "Whereas the verb 'to mess up' is negative, it is positive to 'mess 'em up,' " says Chip Gobs (Hamilton, Va.). "If someone has a difficult test to take, one might give encouragement and say 'Mess 'em up.' It is akin to saying 'Good luck' or 'Do well.' This expression is sometimes contracted by the practiced users of it to simply 'Smup' or 'Smup 'em up.' "

Got that?

Then you're ready for an examination of chill and its many variations. Let's start simply: chill v. Calm down, dude (Mrs. Bronson's English classes at Wheaton High School); or stay cool, take it easy, as in "All right, man, chill" (Danita McKinney, Gaithersburg). chill adj. Calm, down-to-earth or laid back, as in "Jack is a chill dude" (Kitty Troy, Rockville). chillin' adj. Cool or awesome, as in "Man, that bike is chillin' " (Denise Terry's English classes at Sidwell Friends School, Washington). chilly adj. In step with the times (Mindi McGrath, Charlotte Hall, Md.). chilly most n. Someone who is cool or smooth under pressure; someone who seems not to care, as in "What's up, Chilly Most?" (Danita McKinney, Gaithersburg). chill out v. Calm down, shut up, sit down (Sally Weiland's English classes at Lord Baltimore Middle School, Fort Washington); or sit around and take it easy, relax, as in "After a go-go, we like to go to the Pancake House, eat and chill out" (Diane L. Holt, Alexandria). chill with you later colloq. See you later, see you tomorrow, as in "I told Raymond, 'I'll chill with you later' " (Teresa Powell, Landover).

Linguistic observers are invited to send examples of teen-age slang to: J Street, The Washington Post Magazine, 1150 15th St. NW, Washington, D.C. 20071.