If you think that Teng Hsiao-ping has been just a wee bit undiplomatic in what he has said out loud about the Soviet Union and SALT and "teaching a lesson" to Vietnam -- and some U.S. officials think just that -- you should be reassured that he can't hold a verbal candle to that least diplomatic of high-level visitors we have ever had: Nikita Khrushchev.

The Brussian leader came here for 13 days in September 1959 in the midst of a Soviet-American deadlock over Berlin. Khrushchev had been rattling his rockets and exploting what turned out to be the non-existent "missile gap." He was giving the general impression that war could erupt any day if he and President Eisenhower did not come to terms -- mostly Khrushchev's terms.

In his reminiscences Khrushchev told us he had been "curious to have a look at America," then "our No. 1 capitalist enemy." He said he had felt "as though I were about to undergo an important test." So he alternately smiled and frowned, laughed and roared, talked of peace and threatened war.

He told a White House white-tie dinner -- at which he wore a black business suit with medals -- that a war would cause "colossal damage" and "a world shambles." He roared at a Los Angeles dinner, after that city's mayor provoked him, that "some people don't want to get off the hobby-horse of the cold war and the arms race." And if they refuse "and hang on to the saddle," then remember that it would be "either peace or war" and don't forget that the Soviet Union turns out rockets "by the assembly-line method."

That was a chilly evening, with Khrushchev openly threatening to break off his tour and fly home at once. In the second volume of "Khrushchev Remembers," however, the Soviet leader admitted that later in his hotel room he was "giving vent to my indignation for the ears of the Americans accompanying us," because he assumed the room was full of listening devices. Whether or not they were listening, it worked; the Americans, went out of their way to soothe his feelings and the tour proceeded to San Francisco. When he got there, he was smiling; the crowds had been very friendly, and soon he was boasting that "for the first time in six days of house arrest, I've breathed fresh American air."

The "house arrest" charge sprang from the fact that, of all things, Khrushchev was not allowed to go to Disneyland. There had been anti-Soviet protests earlier in Washington and New York, but they were not too serious. The threats in California were taken more seriously. At any rate, the Russians claimed the Americans called off the visit to Disneyland and the Americans contended it was Khrushchev's security man who was responsible.

Whoever was to blame, the Soviet leader made the most of it. He shouted: "What do you have out there, cholera? Or have gangsters taken hold of the place who can destroy me?"

But that flap was topped by the one over the can-can dance at a Hollywood studio where Frank Sinatra and Shirley MacLaine were making a movie of just that name. MacLaine, wearing a dress that offered considerable cleavage, led a chorus of girls who upped their bottoms in the traditional can-can fashion. Khrushchev, his wife and party watched and smiled, and he pronounced MacLaine "very good." But in a few hours he was indignantly declaring that "humanity's face is more beautiful than its backside."

At the 20th Century-Fox studio luncheon for Khrushchev, he and Spyros Skouras, the film company's Greek-born president, got into a public argument over the relative merits of capitalist and communist societies. Skouras, in heavily accented English, boasted about how far he, a poor immigrant boy, had come in America. This produced from Khrushchev the tale of how "till the age of 15 I tended calves, then sheep, and then the landlord's cows.... Then I worked at a factory owned by Germans and later in coal pits owned by Frenchmen. I worked at Belgian-owned chemical plants, and now I am prime minister of the great Soviet state." It was a marvelous self-revelation about this Russian-peasant-truned-Communist-astivist and how he reached the top of the bureaucratic heap in Soviet society.

In New York, he met the men of business, who defended the capitalist system. To this he snorted: "Every duck praises its marsh."

Khrushchev's escort officer was Henry Cabot Lodge, the patrician politican and diplomat. Lodge, then ambassador to the United Nations, had the rank of major general in the Army reserves. When Khrushchev, himself with the rank of lieutenant general, found this out, he kidded Lodge as "my subordinate." Oldge come back by appearing each day, saluting and declaring: "Major General Lodge reporting for duty, sir." Khrushchev loved it.

While Americans today often are suspicious of the Soviet Union, as the current arguments over a strategic-arms agreement demonstrate, this kind of feeling was much more intense 20 years ago. Eisenhower, who already had met Khrushchev at the 1955 Geneva summit, was determined to break the cold-war pattern, knowing as only that old solider did what a nuclear war could bring.

That the trip was educational for Khrushchev and his fellow visitors is beyond doubt. At the Iowa farm of Roswell Garst, he was openly impressed. (It was here that Garst got so mad at the herd of reporters that he started throwing silage and corn cobs at them.) In San Francisco, the reception was mostly very friendly, but there were some rough moments at a meeting with several American labor leaders, including the man who then headed the United Auto Workers, Walter Reuther, who once had worked in a Soviet auto plant. A sample of the argument:

Reuther: "You exploit the workers of East Germany."

Khrushchev: "Where did you dream that up?"

Reuther: "If you don't exploit them, why should 3 million of them cross the border into West Germany?"

Khrushchev: "You are hopelessly sick with capitalist fever."

The Khrushchev tour wound up at Camp David, where he and Eisenhower exchanged stories about their respective troubles in trying to hold down the demands of their military establishments. The visit ended politely, but with no firm progress on the major issues, though Khrushchev later abandoned his Berlin ultimatums. For some time he plugged "the spirit of Camp David" in claiming a successful tour of America.

Certainly a major result of the visit, and of the Camp David encounter -- and a lasting one, too -- was the intensification of the Moscow-Peking split. Eisenhower and Khrushchev talked about China (nothing was said publicly, however), but they came only to an agreement to disagree. The Chinese nonetheless later charged that just before coming here the Soviet leader had Unilaterally scrapped" a pledge to help China build nuclear weapons. Soon after his visit here Khrushchev went to Peking where, he later revealed, he told Mao Tse-tung that the Taiwan issue could be settled by peaceful means as well as by war. At that, Mao called the United States a paper tiger, to which Khrushchev retorted: "a paper tiger with nuclear teeth."

Five years later, Khrushchev was ousted. He died a non-person in the Soviet Union. But for the U.S. officials, journalists and just plain citizens who saw or heard him, his visit to the United States will never be forgotten.