Dr. Rrruth is on a rrroll. "Hullo? You are on the air," she says with chipmunk cheerfulness into the camera, her little legs dangling off the edge of the couch. Ensues there then a tale of woe from someone somewhere in wired America. Dr. Ruth listens intently. The woman on the phone is saying that her husband has grown cold to her. Dr. Ruth stares with deep concern into the lens. Ah yes.

America is a crazy mixed-up kid. Dr. Ruth is here to help. She will not rest until every one of us is straightened out. Or at least not until almost all of us have watched her television program "Good Sex," now five times a week (plus five repeats) on the Lifetime cable network; or heard her radio program, "Sexually Speaking," now on 45 U.S. stations and nearly everywhere a smash hit; or bought her latest book, "Dr. Ruth's Guide to Good Sex," 100,000 copies in print.

As Dr. Ruth Westheimer herself says, "Sex does sell. What is more interesting than what happens in another person's bedroom?" But Dr. Ruth is a happening for other reasons than that. She is our first true superstar sex therapist, a 56-year-old, German-born, liter-sized, classically educated professor who dispenses extremely explicit sexual advice in a thick mittel-Europa accent highlighted by operatically rolled R's ("rrright!"). And she doles it all out with the matronly innocence of Everyman's Grandma pouring chamomile tea. Dr. Ruth Westheimer is the Mary Poppins of the orgasm.

She is also the cutest thing since Care Bears, a lethal delight and a tireless dynamo who runs her producer, director, cameramen and personal aides a merry chase up the ladder of success. Late last night in New York, Dr. Ruth did her last new live show of the season for Lifetime and afterward was to attend a huge wrap party at a Manhattan disco. If it ran according to form, Dr. Ruth was still dancing and scarfing champagne long after younger legs had buckled. She's only 4 foot 7, but she could probably pin Hulk Hogan in 30 seconds flat.

"And you know, I love it!" she says, backstage at her TV studio, of all the hoopla, just after completing a telephone "pre-interview" for a recent TV appearance with Joan Rivers. "You know, my getting a call from 'The Tonight Show,' and all these things, the clothing, all of this attention, the hairdresser that comes from Saks Fifth Avenue to the set, the makeup -- of course I love it! The limousine that's going to take me home tonight? I love it!"

Being a cover girl on People magazine last month? "I love it!"

She loves it.

"But," she adds, in the stern, schoolmarmy tone she uses to signify seriousness, "I also have a healthy perspective. So that I know when it's over I can look back on this and say I had a great time and now I'm on to something else."

It may not be over for a while. Dr. Ruth is rather deliciously addictive. "I just wanna tell you, I love your show, and I think you're dynamic," said one recent caller. "Me and my wife love your program; we watch it every night," said another. "Good Morning America" has booked Dr. Ruth for three consecutive appearances starting next Monday, an encore for her after previously registering as a smash.

And Lifetime, which now advertises itself as the first Talk Television network, is using Dr. Ruth's impressive numbers to save itself from possible extinction. "Lately she has been going gangbusters," says a spokesman; Dr. Ruth is seen weekly in nearly 2 million homes, a sizable showing for cable. "She is consistently our highest rated show," says Mary Alice Dwyer, the innovative program director who frequently shows up for mollycoddle duty at Dr. Ruth's tapings.

"This is not something I predicted, ever," says Dr. Ruth. "I never thought that I would have a radio program. I never in my wildest dreams thought that I would have a television program. If you would have told me a year ago that People magazine was going to put me on the cover, I would have said, 'Who are you kidding?' " She giggles a teeheehee that suggests a Munchkin rising from behind a painted flower.

Dr. Ruth does not mind being called cute. "No! I love it!" However, she did not like being called Granny Freud in a newspaper article. She would prefer to be called Auntie Freud since she is not yet a grandmother. Despite the bluntness of her sexual vocabulary on the air, Dr. Ruth dispenses a basically middle-of-the-road sexual philosophy ("I am very much old-fashioned"), sometimes counseling virgins to hold out a little longer ("What's the rush? Wait!"), promoting her pet causes of "sexual literacy" and contraception ("Are you using a contraceptive? Well, brrravo to you"), reminding her callers that she is not a medical doctor when they get too technical.

With all of her commitments, Dr. Ruth insists on maintaining a private practice as a therapist and an adjunct professorship at New York Hospital-Cornell University Medical Center, where she was trained by her much revered mentor, Dr. Helen Singer Kaplan.

No slouch or huckster, Dr. Ruth also studied at Columbia University and the Sorbonne. Having been smuggled out of Germany with 99 other children during World War II, her parents victims of the Nazis, Dr. Ruth lived in Israel before and after its independence and was a member of the Haganah. She is a rrremarkable woman.

But why this enormous fame and popularity? Electronic sex therapists have been a dime a dozen for years.

"One thing I think that comes across is that I have a certain joie de vivre," Dr. Ruth understates, sitting in a tiny dressing room near her ironing board. "I always have. I know when to be sad, and when to be serious, but I also know when to make the most out of a situation. Also, I think I have guts. I'm willing to speak about those things that people did not talk about. Now, something that I am not responsible for, but that is good for me, is my accent. You know, I didn't choose it, but I think in this country, my accent has helped me. People think about Freud and psychoanalysis when they hear me."

Yes, and it does somehow defuse the words to hear them pronounced "ejacko'late" and "philah-chee-oh."

Backstage is a jolly place on the "Good Sex" show. Dr. Ruth's cohost, the quietly invaluable Larry Angelo, will go so far as to rush Dr. Ruth's dinner in to her ("Larry, you take good care of me," she flirts). And she in turn brings him Havana cigars from Paris, where lately Dr. Ruth has been commuting, as if she weren't busy enough, to film a role in "A Woman or Two," a French comedy.

"Larry! Larry!" she sings out after spilling the beans about the cigars. "I'm going to prison! Because I told that I was keeping you in Havana cigars!" Then she also says that never in her "wildest dreams" did she think she'd ever be making a movie with Gerard Depardieu, and so on. Location filming now moves to New York, which means Dr. Ruth won't be riding the Concorde every two weeks any more.

Her personal publicist, Pierre Lehu, is nearby, as is her husband Fred, a soft-spoken engineer. "Fred, go eat with Larry," she orders him when it's time for her to be interviewed. Later, Fred is dispatched in a taxicab to rush back to the Westheimer apartment when it is realized Dr. Ruth has the wrong dress for the next taping. Because part of the show was already taped, the dresses in both segments must be the same.

A longtime assistant, Marga Kunreuther, responds to the crisis by running wild through the halls and blaming herself, calmed occasionally by her husband Bill (Dr. Ruth introduced them to each other 20 years ago, it is stated by an associate) and by Dr. Ruth, who says, "Relax, Marga, relax."

The format for "Good Sex" consists of this: Dr. Ruth talking. First she takes phone calls, then she interviews her guest star. Past guest stars have included Helen Gurley Brown, Burt Reynolds ("Boy, does he kiss well," opines Dr. Ruth), Gloria Steinem, Henry Winkler, Erica Jong, Willard Scott, New York Mayor Edward Koch and a host of others. When Dr. Ruth returns in the fall, her first guest is scheduled to be Joan Rivers, though Dr. Ruth confesses of Joan's IUD humor, "I don't like those jokes. I don't like that. But I want to tell you something: If the public wouldn't want it, she wouldn't be there."

Then the program continues with a therapy session in which actors play the roles of people with problems. Dr. Ruth prefers using actors to real people because "I don't want people to be entertained by somebody else's misery." Then back to more phone calls. In recent weeks Dr. Ruth could be heard giving out all kinds of advice:

"We are going to do some snuggling without leading to a sexual episode."

" 'Casual sex' doesn't sit right with me. 'Casual sex' means to me like having a cup of coffee. And we do know that sexual activity is more than just saying 'hello.' "

"Fantasies are okay. If you want to believe that a whole football team is in bed with you, that's fine."

"Make believe it's an ice cream cone."

"All right, I would say to the toddler, 'Mommy and Daddy are making love, we'll be out in a little while.' "

"Men, all of you are ignorant! You are constantly worried about the size of the penis. Let's shout it from the rooftops: The size of the penis has nothing to do with the sexual satisfaction of the woman."

"Oh, that's good," roars Leon Dobbin, director of the program (and Dwyer's husband), in the booth. There are some giggles and wisecracks in the booth while the show is being taped, but mainly there is a friendly respect for the good doctor. On taped shows, ads are placed in newspapers to solicit calls for the appropriate taping time. On live shows, Dr. Ruth averages between 2,000 and 3,000 calls an hour. Only a few, of course, get to hear her say "You are on the air."

It was Fred Silverman, of all people, who first thought of putting Dr. Ruth on the air, she recalls, but that show didn't work out because it cost too much. "And now I think, poor Fred Silverman, I feel really sorry, because after all it was his idea," and he has no stake in the new program. "But I'm on good terms with him. He came to my book party. He sent me beautiful flowers."

Dr. Ruth has two children, a 28-year-old daughter and a 22-year-old son, who's at Princeton. She says she never could have managed this whirlwind career when her children were still living at home. Asked if she knows at what ages they lost their virginities, she giggles. "No. My children's sex life is their business. Not mine. I try not to talk so much about sex at home."

And at parties? "I get always somebody with a stupid joke and I stand politely for two seconds and I smile. I wait for the end of the joke and then I go on to different conversation. But I don't have to say 'No sex.' Some of the things I hear at parties are interesting. I want to hear them."

Dr. Ruth is against the use of drugs, and she says she cannot deal with sadomasochism nor countenance pedophilia. But everything else is all right with her. She shocked David Letterman into near stupor when she told him on his program that there were proper nonculinary uses for the cucumber. Letterman, who is one of Dr. Ruth's best audiences, was invited to last night's party but he is in California preparing next week's shows. At yet another party last Monday night in New York, Dr. Ruth ran into retired general William Westmoreland, who, Lehu claims, not only recognized her but told her she'd been "very helpful."

From Charleston, S.C., yesterday, Westmoreland said the remark was only "banter" and that in fact he'd never seen Dr. Ruth's show all the way through. "I turned around and saw this tiny little lady," he recalled. "Frankly, I don't know what she does." Still, it makes a nice story.

As much as she is luxuriating in her celebrityhood, Dr. Ruth is very serious about her subject and her mission. On the matter of contraception, she is an adamant advocate. "I would love to be the first one to do the commercial on condoms on television or on diaphragms," she says. In fact, she was asked, but declined a company's offer when it was specified she would have to say one brand was better than another. Networks and most stations refuse to accept commercials for birth-control devices, but Lifetime accepts them and has aired them on Dr. Ruth's show.

Sitting on her dressing room couch, smacking her lips on chicken brought in by Angelo, Dr. Ruth willingly comments on almost anything.

The "pro-life" movement: "I myself don't like people to have abortions. But abortion must remain legal as a measure for contraceptive failure. I am very upset about this nonsense of bombing Planned Parenthood centers and things like this. That's not what we need in this country. What we need is everybody to pull together and find a good contraceptive and good sex education."

Porno movies: "I tell patients in my private practice, I say sometimes, 'Go and get a sexy movie for your VCR, watch it, and see what happens.' I also teach people that women do get sexually aroused by sexually explicit material, but women most of the time want a story, they don't want just to see sex."

Women's liberation: "I think it did a fantastic job by raising the consciousness. In other things, some of the militant feminists did a disservice because I see women in my office, very unhappy, because they listened, and they are professionally on the top but, they are not married. They don't have children. And in their late thirties, now it's too late."

The Ann Landers survey that found women prefer hugging to sexual intercourse: "Ann Landers' survey is dangerous. I didn't say Ann Landers is dangerous, because that's like saying apple pie is dangerous. It was a dangerous survey because it didn't say 'once in a while,' 'once a week,' 'once a month,' whatever. And I just brought here Match from Paris where the headline was 'American women are frigid.' What nonsense is that to say American women are right back in the Victorian age, where the Victorian mother tells her daughter the night of the wedding, 'Lie back and think of England. There's nothing in it for you.' "

Dr. Ruth also says she does not think Americans are more messed up sexually than people in other countries and, indeed, that the existence of shows like hers proves that we are all growing up. "This whole idea of 'the Latin lover,' 'the French lover,' that's a lot of baloney," she scowls encouragingly.

Nor is she concerned that, despite (or because of) viewer advisories warning of adult material, some children might see her program. "What I hope is that people of that age will listen a few times, 'ha ha ha, very funny,' and then go on to other things," she says. "A 6- or 7-year-old is not going to be interested. Is the program ever sexually arousing to a kid? I think maybe at a preteen age, probably not. I'm not saying they don't masturbate, but probably not. A teen-ager, it might. But that's another thing why I'm successful. I certainly am not a sex symbol. I'm not a tall, blond, voluptuous pinup girl."

Dr. Ruth's new book of sexual advice for teen-agers, "First Love," will be out this summer. Dr. Ruth keeps busy.

At Lifetime cable network, she is treated like a goddess because at last they've come up with some original cable programming that people actually watch. Dr. Ruth has had to face the possibility that some network might come a-wooing with a much more lucrative offer. What if ABC told her that she'd make a swell daytime show for them? "Then," says Dr. Ruth, "I would have a problem. But it hasn't happened yet."

The crucial dress for the taping now having long since arrived, and Dr. Ruth having gone through makeup cheerfully, and her assistant Marga now running around looking for the right necklace to match the previous taping ("Marga, relax"), Dr. Ruth is ready to face the camera again, and it seems obvious the camera is not only ready but eager to face her. "I think that people try to make the best out of their lives," Dr. Ruth says. "I'm very much an optimist. I could not educate the way I do with enthusiasm if I would think that this is a sick society that needs help."

She summons the program's towering floor manager, Dean Gordon, for their regular pretaping ritual. Dr. Ruth insists on being led arm-in-arm down the hallway to the studio, and then Gordon is to stop, turn to the feisty, zesty, lusty little lady, and tell her that this is going to be a wonderful show. They walk, he turns, looks down and tells her just that. She beams, appreciative.

It looks like a wedding procession. The bride is not blushing.