CALL IT beginner's luck or comic karma: an unknown named Schwartz knocked 'em dead at Garvin's on open-mike night.

"You here to perform?" the manager asked.

"Yeah."

"Where else have you been?"

"Nowhere." No acting class, no high school drama credits, nothing but a turn in the chorus of 50 screaming summer campers.

"What kind of stuff do you do?"

"I'm just going to try to keep it short, get on and get off."

The lure of the lights. I am drawn to the stage the way some people are compelled to run Bonnie Bell marathons. As long as I finish with dignity, I will consider myself a winner. It seems easier than talking at parties.

With luck, my monologue will probe some uncharted feminine quirks, not self-deprecating but rooted in urban angst. Never mind the "she was so ugly/fat/stupid" overstatements that traditionally bombard Catskill audiences. I'm planning to talk about emotional wear and tear, aiming for a cross between Joan Rivers' shrewd sarcasm and Lily Tomlin's insight. They are masterful: Tomlin worries that the person who thought up Muzak may be thinking up something else . . . Rivers says she was inviteed to Prince Charles and Lady Di's wedding because of her legs -- "they needed something old and blue." The pain of comedy is never far below the laughter.

Take Henny Youngman, please. "My wife has an even disposition -- miserable all the time." Is his approach funny in 1981? I prefer dry wit to rapid-fire insults. But Rodney Dangerfield, hero of the put-upon, now there's a sucker who strikes a nerve while getting no respect.

The amatuers at Garvin's, at 2621 Connecticut Ave. NW, worship and borrow unconsciously from well-known comic types en route to developing a style.Open-mike night, their night, is Thursday. As they gather at 8:30 for the show that never starts promptly at 9, the regulars regard the newcomers warily though not unkindly.She is the only female performer in the room. Full name? Funny, all those months threatening to do a one-night stand-upm and she never imagined a stage name. A little guy named Jerry suggests Schwartz. Yes, Joanne Schwartz.

At 9, emcee Dan Brenner sternly commands the attention of the 12 comics, including a juggling clown and a magician. Brenner, by day an FCC attorney, has a shtick that covers fast food and a possible singles magazine called "Me, Me, Me." But nothe structs the performers to finish their acts when the eight-minute light flashes so that everyone gets on before the crowd turns to moss. Eight minutes sounds like an eternity. It takes two seconds to trip on a mike chord, Schwartz figures.

As a first-timer, she begs to be separated in the lineup from the professional comics from New York. Brenner offers a place following the clown. The clown has a red Nerf-ball nose, plaid baggy suit and a surprisingly limited repertoire of funny faces. Perfect.

A jittery cab driver, making his debut also, argues with Brenner over the meager eight-minute allotment. He claims he's got 10 minutes of dynamite stuff. Brenner's playing the heavy. Is there a hook hidden behind the red curtain on-stage?

A case of nerves is contagious. The guy next to Schwartz breaks into his Rod Sterling impersonation. A seasoned sleight-of-hand artist pulls a quarter from someone's ear. The little guy, Jerry, is trying to engage Schwartz in conversation, looking for someone to tape record his act.

Schwartz is silent. Eager regulars shake her hand, make introductions, size her up. One turns to her and asks, "Nervous?

She excuses herself, orders a vodka tonic and sucks a lime. In fact, she is not nervous, feels nothing. Out front, the room starts to hum with 75 customers paying a hefty $3 cover and starting on the two-drink minimum. So far, the waitresses are sweating more than Schwartz is.

From the back of the room, she can just see Brenner warming up the crowd. Behind the scenes, the regulars grumble about the management's new policy: no sitting in the audience until after you've been on, and performers' dates will be charged the drink minimum. "Let's boycott the place," Jerry says. Club policy does not concern Schwartz at the moment.

First act Chris Truitt has had better evenings. The baby-faced comic in Lacoste shirt slings his lines: "I know what you're thinking: 'Chris, you're just not preppy enough for us' . . ."

Schwartz is eight minutes away from her spot now, smoothing her violet seersucker shirt, black slacks and white jacket. She skids in medium-high heels on wet wood in front of the bar, flailing for balance. Is this an omen?

At the waiting position off stage-left, three or four of the regulars offer hugs and whispered words of advice. "Relax and have fun with it." "I'll be up front making faces at you." Schwartz measures the obstacle course to the stage, wondering which chair, wire or customer will trip her first.

The clown is juggling knives, his makeup dripply under the lights; he tosses glow-in-the-dark bowling pins, then cleavers. He jokes about being a waiter at Benihana's. Schwartz is next and she isn't even shaking.

As Nerf-nose leaves the stage, he grabs her hands and wishes her luck, still wired from the limelight. Brenner is already winding up: " . . . warm welcome for the comedy of Joanne Schwartz!"

There is applause, an empty platform, a microphone, thoughtfully lowered. Beyond, a sea of darkness. Schwartz jumps uneventfully onto the stage and lifts the mike out of its stand. Just like the last time she played the Copa . . .

"Hey kids! [beat] A funny thing happened on the way to Garvin's tonight." Surprisingly, her voice is still functional. It's a live microphone, a live audience. Schwartz launches into her feminine hygiene spiel. In the glare of the hot lights, she squints, looking to make contact. They are laughing. A women in the front row is roaring, her head thrown back. Focus on that laugh, Schwartz.

"As far as I can tell, cramps are purposefully kept out of the news. For instance, this item taken from the AP wire didn't make it in any local papers. [Pulling out an actual wire clip from her pocket] Dateline, Atlantic City. 'A state geologist says hundreds, perhaps thousands of plastic tampon applicators are washing up on New Jersey's beaches . . .'" From there into other problems of female singles, including the bachelorette refrigerator. "Luckily a team of archeologists from down the hall was able to do some carbon-dating on the piece of cheese . . . they also turned up a liquefied head of lettuce and some celery Slurpee marking time."

"You're hot!" says a voice from the crowd.

She ad libs. Tests out her fantasy TV commercials and thoughts on adolescing on the mean streets of Bethesda. "The three blacks in my high school class were so well assimilated they took off for Yom Kippur . . . Any other local yokels here?" A few scattered responses. "Cutters!" Some minimal chuckles. Schwartz presses on.

"I used to sing the Beatles' song, "And when you touch me I get happy inside, it's such a feeling that, my love, I get hives .'

"But I'm much more sophisticated now, I'm working on a screenplay called 'Herpes: The Movie.'

From deep space, a light flashes, Schwartz stumbles through another couple of sentences, ends abruptly with the unanswered query, "Where do dustballs come from?" and replaces the mike with thanks and supreme relief. She thinks only of remaining on her feet, as she steps down from the stage. A flood of applause carries her out of the room.

Out on the sidewalk, trying to catch my breath in the steamy air, I'm approached by manager David Filvarof, who asks if I've played other clubs and whether I'm interested in making this a regular thing. I should keep performing on open-mike night (moving to Sundays starting in July) and watch the professionals on Saturdays, he says -- "no cover."

The clown fashions a dachshund out of a long red balloon and presents it as an reward. I leave with the dog and a kick: I'll be high for a week on the laughter.

Home after the show, I am awake all night. at dawn I replay my tape and begin to scribble notes for new material.Everything seems a potential monologue in my overtired haze.

The next week, Schwartz returned to Garvin's. She didn't get on until 11:30 -- after a brilliant young comedian from New York who's even been on Carson. She had a tough time with the tired, laughed-out audience; her idea for a country-punk nightclub (Crystal Gayle singing "Don't It Make My Brown Eyes Black-And-Blue") hardly got a moan. The words of emcee Brenner echoed in her ears: "Until you've bombed a couple of times, you haven't really done comedy."