Gary Herb is acting angry. His eyes flash fire and he marches from the stage at the Waaay Off Broadway down into the audience, trailing his microphone on a long cord. A woman in the audience has just telegraphed the punch-line of one of his "jokettes." He stalks to her table and towers over like a Druid intent on human sacrifice.

"What is your name?"

"Linda."

"Do you know any more jokes, Linda? Tell me a joke I haven't heard -- and it had better be funny."

Linda reaches out a hand placatingly to touch this sensitive man whom she has offended, and he cuts her off with a mock-curt sentence:

"Unh-unh, Linda -- I'm not into broads."

Herb (the bearded one) is one-third of Gotham, a gay trio that has been delivering song-dance-and-raunchy-joke routines for 6-1/2 years now and has become a Washington fixture for several months each year -- usually at the Waaay Off Broadway, but also at the Cellar Door and even in the Kennedy Center Concert Hall.

Linda is a part of the group's new straight audience that has slowly been growing ("married couples from Bowie" is how Gotham describes them) until they now constitute a substantial majority.

A few years ago, straights used to come in relatively small numbers to be gently insulted."Are there any straight people here?" a member of the trio would ask. A few timid hands would go up, and they would be praised for their courage, ridiculed for the "funny" way they walk, and grudgingly accepted because, "where would we be without them?" Now, they come because they have learned that there is nothing else quite like an evening with Gotham.

Gotham was originally formed in New York by Herb and Michael Pace (the short one), who saw an opportunity to be paid regularly for being themselves and who plunged into the gay entertainment ghetto to do so. David McDaniel (the tall, quiet one who often serves as a straight man for the other two) joined the group in response to an ad for "the deepest voice in New York City."

Now all three are in their late 20s and, if they have not exactly broken out of the gay ghetto, they have helped to enlarge it beyond recognition. "A few years ago," says Herb, "it became chic to go to gay bars to see us -- like socialites going to Harlem in the '20s. Now, our audiences are more straight than gay."

"But I hope the gay crowd will never leave us," says Pace.

"You'd have to drive them away," suggests a friend, and McDaniel smiles in agreement.

In their transition from specialized cult figures to the entertainment mainstream, Gotham's members have been riding the crest of a wave of interest stirred up by Bette Midler and increased by unisex styles and increasing gay pride and candor. Asked where they stand on the spectrum between closet and militancy, Gotham will answer "honest." There may be less specialized material in their act now than there was a few years ago, but any changes are subtle. There are no Anita Bryant jokes anymore, for example -- but that is because Anita Bryant no longer gets a laugh.

Asked what achievement might make them consider themsleves a success, the members of Gotham came up with a variety of answers. "When we appear on the Merv Griffin show," suggests McDaniel (they have done that twice). "When we have a hit record," offers Pace (their new record, "Void Where Inhibited," is selling briskly).

Other suggestions: "When we can sell out the Tyrone Guthre in Minneapolis" (they do that regularly); "When we can pay the rent" (no problem at the moment).

The act that pays the rent is a mix of music, off-color jokes and insults to members of the audience, usually delivered by Herb. "I swear," he tells a man in the front row, "if you were alive, you'd be a very sick man." Then he turns to a woman: "Look -- a blond. Do you speak in sentences?" She tops it, perhaps, by saying "No."

At one point in the show, the group usually does their "Henny Youngman" segment -- a series of rapid-fire one-liners that they climax by going into the audience and asking for jokes. "We get a lot of little old ladies," says Herb, "who tell dirtier jokes than we would dare. I have a theory that everybody wants to stand on the stage and tell a dirty joke, and we give them the chance."

"The female of the [straight] species is dirtier-minded than the male" according to one Gotham theory -- or at least more willing to speak dirty jokes into a microphone in the dim anonymity of a cabaret.

That's how it was on one recent evening at Waaay Off Broadway. All but one of the volunteers from the audience were women, and most of their jokes were rauchier than anything they had heard from the entertainers. Some were doubly offensive -- for example, one about a Polish bank-robber that both modesty and ethnic sensitivity forbid retailing. "Write it down," Pace shouted to an invisible colleague backstage.

He later confided that the group gets a lot of good material that way, free of charge. But for the moment, the group merely looked shocked, and McDaniel asked the audience: "What are you people doing here" We're getting paid for it."

Their current visit (scheduled to end on Jan. 20) is probably the last time they will be paid to be at the Waaay Off Broadway, which is going out of business -- not for the first time, but possibly for the last. Across the country, the gay cabaret scene is failing -- some places are closing because of a cost-price spiral; others are merging into the straight scene as gay chic becomes a part of everyday show business and some are dropping live entertainment and going disco.

While it is doing more and more performances in concert rather than cabaret form, Gotham is also making the disco scene via its new album for Aurum RECORDS AND A SINGLE FROM IT, "AC/DC Man," is getting considerable play as a response to "Macho Man." The lyrics (ostensibly about an electrical repair man who works at night) cleverly exploit double-entendres.

The motif underlines the group's double-threat appeal. While they welcome mixed audiences, they adhere firmly to the gay identity. There is no evasion or defensiveness but a sense of privacy in their discussions of the topic.

Their success is an indication of a changing culture.

The performing arts traditionally have been regarded as a sheltered sanctuary for homosexuals. This places Gotham in a venerable tradition -- but they and a few others are radically changing that tradition.

The change is that they no longer have to pretend.