What was going on when I was born?

The Nicaraguan Government expelled three American diplomats today, charging one with overseeing a ''macabre plot'' to kill or incapacitate the Foreign Minister. All three, according to Lenin Cerna, the Government's security chief, were using diplomatic cover while working for the Central Intelligence Agency. He said they were building a ''counterrevolutionary network'' whose members were to have formed ''terrorist commando squads to carry out attacks on our leaders.'' The United States Embassy rejected the charges ''in most emphatic terms'' and asked the Nicaraguans to rescind the expulsion orders, which it said ''directly contravene the most basic norms of diplomatic practice.'' An embassy spokesman, Gilbert Callaway, described the charges as ludicrous and ''all lies.''

The Reagan Administration plans to liberalize the criteria for paying Social Security disability benefits to people with physical or mental handicaps, Administration officials said today. The announcement, they said, is to be made this week by Margaret M. Heckler, the Secretary of Health and Human Services. It comes in response to criticism by members of Congress of both major political parties, who denounced the termination of benefits for people with obvious disabilities. The steps contemplated by the Administration, described by one Health and Human Services official as a ''capitulation'' to the critics, would restore some of the policies that prevailed before President Reagan took office. But it appears that the rules would still be stricter than in the Carter Administration. The new measures would not alter the 1980 law under which disability beneficiaries must be re-examined at least once every three years. The Social Security Administration began conducting those reviews in March 1981, after Mr. Reagan took office.

The Supreme Court upheld the ''windfall profits'' tax on decontrolled oil, providing a substantial victory for the Treasury. The tax has yielded about $30 billion since 1980 and is expected to yield that much more over the next six years. (Page D1.) The Justices also ruled that Federal regulators need not weigh environmental consequences of waste disposal in licensing new nuclear plants. (B7.) Speaker of the House Thomas P. O'Neill Jr. proposed that the tax cut due to take effect July 1 be limited to $700 for each taxpayer. The proposal drew a political battleline with President Reagan, who has promised to veto any effort to tamper with the reduction in tax rates. Mr. O'Neill stressed that his proposal is meant to maintain a relatively heavier tax burden on wealthier citizens. (A1.)

A particularly poignant and troubling problem in the medical profession is that of the doctor whose easy access to drugs leads to his own addiction. What follows is the story of Dr. William J. Farley, one of the rare physicians who has been willing to reveal his experience. When William Farley was growing up in Trenton, Ontario, he had an extraordinarily intimate view of medicine. His great-grandfather, grandfather and father were physicians in the same town about 100 miles east of Toronto, and his grandfather was president of the Ontario Medical Association. But he saw a sordid side of medicine. His mother, a nurse, was addicted to morphine, alcohol, codeine and other drugs, he said. Sometimes she took doses so large she had to be treated in a hospital emergency room. More than once her reactions were so severe that the young Farley was told his mother was on the verge of death.

The Pillsbury Company said yesterday that it would acquire Haagen-Dazs, a family-owned ice cream chain with an elite image, for an undisclosed amount of cash and notes. William H. Spoor, Pillsbury's chairman, who was in New York yesterday to make the announcement, said that his company had been searching for acquisition targets for months to round out its diversified food business. ''We spent weeks going through the 8,000 companies'' on our list, Mr. Spoor said. Haagen-Dazs, he said, had the elements that Pillsbury was looking for, including a franchise network of 244 ice cream stores, strong supermarket presence and corporate growth of about 30 percent a year.

Governor Cuomo said today that there was little chance that his program for taking control of the board of the Metropolitan Transportation Authority could pass the Legislature over the objections of Mayor Koch. ''Very, very difficult,'' said Mr. Cuomo. ''It would be extremely problematical that we'd get anything changed that effects the City of New York with the Mayor's opposition.''

At the start of the busy summer air-travel period, the United States Customs Service yesterday formally began a new procedure at Kennedy International Airport that it says moves travelers through customs 50 percent more quickly and is also more effective in catching drug smugglers. The procedure has a ''red-green'' system, popular in many European cities, that uses two lines - red for those with items to be declared and green for those with nothing to declare. Baggage on both lines is still subject to spot inspections by customs agents. But the aisles have been widened so that only those bags that the agent asks to see have to be lifted for inspection. Under the old procedure, all bags had to be placed on the agent's counter.

An article in Business Day Friday about John M. Fedders and the Southland Corporation incorrectly reported the terms of a grand jury indictment of the company, one of its executives and a former New York City Council member. It charged conspiracy to bribe a New York State tax official.

Leaders of an official Anti-Zionist Committee set up six weeks ago said today that they were satisfied that Jewish emigration had effectively stopped because most Soviet Jews who wanted to leave had gone. Speaking at a news conference, Samuil L. Zivs, the group's first deputy chairman, said assertions in the West that thousands of Jews still sought to emigrate represented ''juggling of figures by Zionist propaganda.'' (The National Conference on Soviet Jewry, a New York-based group that monitors emigration statistics, says that by late 1979 at least 300,000 Jews had asked relatives abroad to send invitations to emigrate. It is not known how many of these have since gone or still want to leave.)

Stanford University's expulsion of a graduate student, on the basis of a secret report by faculty members who investigated his anthropological work in China, has touched off a dispute about academic freedom. The student, Steven W. Mosher, was dismissed from Stanford's doctoral program by an 11-0 vote of the anthropology department last February, with no reported dissent. But the secrecy surrounding the decision and conflicting accounts of the charges against the student have raised questions over whether Stanford had bowed to pressure from Peking to retaliate against Mr. Mosher. Mr. Mosher, 34 years old, conducted research in a village near Canton in 1979 and 1980. He was one of the first American scholars allowed to work in China after normal relations between Peking and Washington were restored.

One night in 1933, Richard Hollingshead Jr. took a projector outside, flashed a movie on the side of a building and sat in his car to watch it. Friends and family were very worried about Mr. Hollingshead. He next patented a ramp system allowing the occupants of a car to see a screen over a car in front of them, and on June 6 of that year he opened the world's first drive-in movie theater, the R.H. Hollingshead Jr. Theater on Admiral Wilson Boulevard in Camden, N.J., showing ''Wife Beware.'' History did not record the first young couple unable to tell their parents what movie they saw at the drive-in, the first family bringing children in pajamas, the first teen-ager to enter a drive-in theater in a car trunk and leave with a purloined speaker. But oldtimers in the business said all of those things happened early on and continue today.

The chairman and chief executive of Norton Simon Inc., David J. Mahoney, is heading an investor group seeking to buy the big consumer products concern for $1.65 billion and convert it into a private corporation, the company said yesterday. Stockholders would get only $738.8 million of the total offering price, or about $29.50 a share. The rest would be used to pay off company debts and for working capital once Norton Simon went private. Last year, the company reported a sharp decline in earnings, in part because of losses at its Avis rental car subsidiary, which accounted for 28 percent of fiscal 1982's $2.9 billion in revenues.