It is gallows humor time at the Club 58. Gunmetal Fizz, three white performers specializing in arch wit and arched eyebrows, sing paranoid ditties about the decline of the rand, the effect of tear gas on a suburban lawn -- "have you seen what that stuff does to your lounge furniture?" -- and the possibility that their black gardeners may arise someday in a Spartacist revolt.

What to do? Gunmetal Fizz suggests learning karate, building a stone wall topped by broken glass around the yard, stowing hand grenades under the pillows and socks filled with ball bearings by the bed, and setting up steel traps on the lawn.

"White and rich," one song laments, "is no longer fun."

In real life, things are not quite so bad in South Africa's largest city. But the restless worry, morbid humor and general helplessness captured in the broad strokes of the cabaret revue are common features of white middle-class life.

"At the moment, it's like being wrapped in cotton wool," said David Dalling, veteran member of Parliament for the opposition Progressive Federal Party. "Whites are living in a bed of inertia. They are complacent but also uneasy, and they don't know why. They are worried, but they don't know what to do, and those who do are leaving."

Along with cracking down on black radicals and township unrest, the government's five-week-old state of emergency also was designed to reassure its bedrock white constituents that Pretoria had the situation under control. The emergency decree was accompanied by an emotional plea from President Pieter W. Botha for unity and loyalty in the face of adversity.

But, although the emergency restrictions outlaw statements that undermine public confidence, reassurance is hard to come by these days in white South Africa. Instead, the signals were widespread this past week that something is unraveling:

Following the recent spate of terrorist bombings, freshly painted signs went up at every entrance to Sandton City, the country's largest suburban shopping mall, warning customers that security guards would be checking their packages for explosives. "Safety comes first at Sandton City," said the not-so-reassuring signs.

Local newspapers reported that, for the first time since the Great Depression, unemployed whites are lining up for day labor jobs that pay 40 cents an hour. Inflation is nearing 20 percent, the gross national product is shrinking, and Botha regularly questions the patriotism of his critics in the white business community.

The government released new figures indicating a net outflow of 2,157 whites for the first four months of the year, more than double the previous record. Although the overall emigration numbers remain low, South Africa lost 162 engineers, 27 doctors and dentists, 70 accountants, 95 teachers and 161 managers and administrators, most of them under 40.

"People are going anywhere they can," said a manager at a local moving company who, based on his own manifests, believes the actual number of emigrants far exceeds the official count. "They are frightened, they want out and they don't much care where."

South Africa's 4.5 million whites may constitute a ruling class that has maintained power over the years through a ruthless and relentless system of racial segregation, but they are an increasingly fractured and diverse group. They range from native-born Afrikaners to descendants of English colonists, from sophisticated urbanites to cattle ranchers and corn growers.

There are liberals like Dalling, a suburban insurance executive who said he looks forward to the days of black majority rule, and small-town rightists like Eugene Terr'Blanche, who celebrates ethnic purity and speaks in thunderous tones of an apocalyptic race war.

What many of them have in common is the sense that they are a minority under siege. Their newspapers, sensing a trend in the making, are filled with articles about private security firms, armored cars and sharp increases in handgun sales. White South Africa, one headline blared, is preparing "for a lifestyle in which guards and bombproof bakkies pickup trucks will become as common as rugby and sunny skies."

Most whites also share a profound lack of knowledge about what is happening in the troubled black townships that are sealed off from their sight and their consciousness by geography, politics and years of social custom.

Whites live in a separate universe from their black countrymen, said Helen Suzman, Dalling's parliamentary colleague, "and in the vast majority of cases, the white citizens have never set foot in the world of the blacks." Most know nothing about conditions in the townships, "the wretched, overcrowded houses, the inferior schools, the unpaved streets, but most of all they know nothing about the seething anger that has built up over the years, so clearly demonstrated at funerals."

Among the most ignorant, said Suzman in a recent speech, are members of the ruling National Party. "It would be a salutary experience for every Nat MP member of Parliament to attend a black funeral, heavily disguised as a human being," she jibed.

Sometimes the two worlds briefly and incongruously touch. Winnie Mandela, wife of the imprisoned black nationalist leader, paused to hold a press conference with foreign correspondents late last year at Jan Smuts Airport here after returning from her latest visit with her husband Nelson. For many years Winnie Mandela had been banished to a remote rural area, her name and statements banned from publication.

As reporters gathered and cameras flashed, Anneline Kriel, the blond former Miss Universe, strolled by. She paused briefly to listen, a quizzical look on her face, then walked on.

"I was just curious," she said later, adding that she had never heard of Winnie Mandela.

This city, South Africa's largest and ostensibly its most liberal, reflects the ambivalence many whites feel about blacks. Its parks and libraries were integrated 11 years ago when apartheid was still entrenched beyond debate, and some of its neighborhoods are decidedly, albeit illegally, mixed. But its buses, health clinics and swimming pools remain segregated, as do most of its recreational and sports facilities.

In recent weeks, the Financial Mail reported, Indian golfers have been barred from the municipal golf course, and a woman of mixed race had to get a special permit to attend an aerobics class at a community center. Such incidents contribute, the magazine said, to the image of Johannesburg as a city of "sympathy without action . . . stealthy and shamefaced."

If anything, the state of emergency has made communication between whites and blacks even more tenuous and uneasy. Articles on black unrest have all but vanished from the news pages, except for official pronouncements from the state Bureau for Information, which takes pains to preface any bad news with the claim that the number of unrest incidents is actually falling, although it never releases the figure.

In such circumstances, dissent can be risky. Harald Pakendorf, the liberal editor of the Afrikaans-language afternoon daily Die Vaderland (The Fatherland), lost his job recently because the newspaper's board of directors deemed him too critical of the government.

But while the government has largely succeeded in controlling the flow of news and opinions to its white constituents, it appears less successful in galvanizing whites. The unveiling of the new South African-made Cheetah jet aircraft last week, accompanied by much official fanfare and patriotic exhortations, was greeted with a collective yawn by the public. Even Beeld, the region's largest Afrikaans daily that is often accused of being a government mouthpiece, consigned the Cheetah to page two.

Unlike the United States, where skepticism about government is a way of life, whites here traditionally treat their political leaders with unquestioning reverence and respect. That faith has been badly shaken in recent years.

A recent poll of urban whites by the Markinor marketing firm here found 54 percent of those surveyed approved of the government's handling of township unrest and racial conflict, but the approval rating dropped to 38 percent when the issues were inflation and unemployment.

The results may not matter very much, because the Botha government, which has not faced an election since 1981, can delay a new one until 1989. Those whites who feel that something has gone badly wrong, have little recourse until then.

A young Afrikaner woman who holds a top position at the state-run broadcast company said: "I feel I have no influence over this government and no say over what they are doing. I don't even understand how they think anymore."

She said the changes she senses have yet to affect her life directly or that of her husband. An overseas trip had to be put off because of the precipitous fall in the value of the South African rand, but their incomes still rise annually and they are still planning to have children. The few terrorist bombs that have exploded downtown may give them pause but have led to no discernible change in lifestyle.

Still, she said, she feels increasingly despondent and worried about the future. "I have this terrible feeling of helplessness," she said.

Roger Lucey, a local pop star, put it this way in a recent song:

You don't have to listen

You don't have to hear,

There's no crime in closing your mind.

The rivers run slowly,

The children are growing,

But it's not safe to plan ahead.