You know her. She's the one who tells host Gene Rayburn to shut up. She's the one who snaps "This question stinks." She's the one who snarls at Betty White: "The answer is virginity' - something you wouldn't know anything about."

And yet, for all her familiarity as the wise-cracking, acid-tongued panelist on "Match Game," (Ch. 4, 5 p.m. weekdays) Brett Somers stands as the Rula Lenska of Game Shows. A mystery woman. An enigma. A celebrity or sorts who can't quite be pinpointed in this TV series or that Hollywood movie.

Attempts to probe her past only deepen the mystery. She doesn't have the standard showbiz bio. She doesn't have her own publicist. She doesn't appear in Les Brown's "Encyclopedia of Television." Indeed, she can't even remember the last time she talked to the press. This may explain why she chose to get dressed up for this interview - even though it was conducted 3000 miles away by telephone from her home in Beverly Hills, Calif.

Bits and pieces emerged from the conversation. She has been a member of the Actors' Studio for more than 25 years - proudly noting she joined the same year as James Dean. She appeared in one Broadway play 20 years ago called "Maybe Tuesday" - but it ran exactly three days. She was in one episode of "Mary Tyler Moore" as Rhoda's Aunt Rose - but wasn't asked to join Rhoda's spinoff series. She played Blanche Madison, Oscar's ex-wife on "The Odd Couple" - but was only on the show occasionally. She was Gertie the telephone operator on "The New Adventures of Perry Mason" - but the series was canceled after 13 weeks. She loved doing her first Purina Cat Chow commercial six years ago - but no one has since asked her to do another one.

But if superstardom has eluded Brett Somers, it has been partially by choice. She was bitten by the show-business bug rather early. Born in Portland, Maine, she ran away to New York at 18. "I got on a train to see the bright lights and put a white streak in my mother's hair." In the '50s, she appeared on all the major television shows - "Philco Playhouse," "The Kraft Television Theater," "Studio One," etc. But upon entering into her second marriage, to Jack Klugman (whom she later played opposite in "The Odd Couple"), she virtually gave up her career to raise two young boys. "My career has always been secondary to my home life and it was always my choice. I wish I could tell you I'm not successful because this is such a terrible business. I wish I could say I never got any breaks. Paramount called me. William Morris called me. But I got on a train and went back to Maine. A lot of it was fear of success."

Her marriage to Klugman lasted 18 stormy years. "Name a public place. We had at least one fight in it: New York, London, Paris. We were both very volatile and competitive." Asked why she refers to her former husbands as "Mr. Right No. 1" and "Mr. Right No. 2," she explains: "I don't like to think of myself as a person who makes mistakes."

Without apologies, thank you, Brett Somers has mostly made a career as a professional panelist on "Match Game" for the past seven years. Goodson- Todman, the show's owners, originally wanted Somers and Klugman (who were still married at the time) as regulars. "They asked if I would come on with Jack. I told them Jack was out of town. So they said: Would you come on alone and mention him a lot?' I said Sure.' "

Somers has few illusions about television. "We're assaulted and insulted by so much of it. Most of it is so mindless." Still, she finds at least one redeeming quality in game shows. "I think they're the last vestige of spontaneity left in television. People feel they're watching something real as opposed to the unreality of all the sitcoms and dramas which are so plastic."

Not that Somers takes herself or her show seriously. It's simply an easy job that pays rather well. She works four days a month, 35 days a year and earns $100,000. By her own admission, she almost never watches the show.

"It's a job. I show up and do it to the best of my ability. I prefer Match Game' to a sitcom where you have to get up at the crack of dawn . . ." Queried about memorable moments, she says: "Oh God. That show goes out of my mind as soon as I do it."

Perhaps the reason why Somers has succeeded on "Match Game" is that she is best at playing herself - an ornery, opinionated, outspoken woman who is not afraid to speak her mind on or off camera. Her targets vary from Saks department stores to Spiro Agnew. "My appeal is that I really don't have anything to hide. When you look at me you may not like me, but you know who's at home."

What with the onset of middle age ("I'm between 48 and death") and having two grown children (21 and 17), Somers wants to broaden her horizons. She is excited about starring in a new play with Paul Winfield in St. Louis called "Happy Ending" and dreams of taking it to Broadway.

One thing is clear. Somers is ready to shed her image. Asked how long she intends to stay with "Match Game," she says: "Oh God, I don't know. I don't want to have to show up there in a wheelchair, I'll tell you that.

THE RULA LENSKA OF GAME SHOWS