What was going on when I was born?

Forget June 21. No matter what the calendar says about its being the first day of summer, the season in the New York City area really begins this afternoon as millions leave for their first trips to beaches and country lanes. Millions are expected to take to the roads in cars, while other travelers jam buses and trains. With an eye toward relieving congestion, the Long Island Rail Road will switch to its expanded summer schedule today. The schedule includes additional trains to the Hamptons and to stations that feed the ferries to Fire Island.

International A withdrawal of the nomination of Ernest W. Lefever as Assistant Secretary of State for Human Rights and Humanitarian Affairs has been requested by Senator Charles H. Percy, the Chairman of the Senate Foreign Relations Committee, according to Administration and Congressional officials. Aides to the Senator reported that Mr. Percy told White House officials that Mr. Lefever might ''hurt the foreign policy goals'' of the Administration. (Page A1,Column 1.) Syrian missiles must be removed not only from Lebanon but also from Syrian territory near the Lebanese border, Prime Minister Menachem Begin said in a television interview. The broadening of demands by the Israeli leader, which included the demand that Syria not fire antiaircraft missles from its own territory at Israeli planes over Lebanon, was expected to complicate efforts to resolve the conflict. (A1:4.)

Prime Minister Menachem Begin today broadened his public demands on Syria, declaring that its recently deployed antiaircraft missiles must be removed not only from Lebanon but also from Syrian territory adjacent to the Lebanese border. In addition, he said, Syria must make a commitment not to fire missiles from its own territory at Israeli reconnaissance planes operating over Lebanon. These demands, made in a television interview with the NBC News program ''Today,'' were expected to complicate diplomatic efforts to resolve the conflict over the missiles. Assad Rejected Earlier Demand President Hafez al-Assad of Syria has already rejected the earlier, more limited Israeli demands for removal of missiles deployed in the Bekaa Valley of eastern Lebanon since April 29, and has strongly criticized the Israeli leader for insisting on their removal.

Treasury Secretary Donald T. Regan and the Democratic majority leader in the House of Representatives, Jim Wright, held out the possibility today of making compromises that might permit agreement on a bipartisan tax bill. In an interview, Mr. Regan said the Administration wanted to write a bipartisan bill with mainstream House Democrats, not just with a group of conservative Democrats from the South.

For the second time in its meteoric 10-year history, the Amdahl Corporation, a small manufacturer of large-scale computers, is profiting from its ability to second-guess the huge International Business Machines Corporation. The evidence can be found on the bottom line: For the first quarter of this year, Amdahl reported an earnings upturn after a rapid twoyear decline. In large part, the company's problems were attributed to widespread speculation that I.B.M. would introduce a large-scale computer system so far advanced that Amdahl, its only major competitor, would be unable to keep pace. But when the I.B.M. product announcement came six months ago, Amdahl immediately proved its doubters wrong.

''My intention is to convince, not to defeat. There was only one victor on May 10 - hope.

The companies project an aura of innocence because they make food for babies. But for years, consumer groups have hounded them, calling them baby killers and mounting boycotts of Nestle, the leader in the sector. Yesterday the critics of Nestle, which is based in Switzerland, and Abbott Laboratories, Bristol-Myers and American Home Products, all of the United States, scored a victory. The United Nations World Health Organization, assembled in Geneva, voted 118 to 1 (the United States cast the sole negative vote) to ban advertising that tends to discourage breast feeding.

Drawn to nature, thousands of New Yorkers are about to renew the summer custom of leaving work early on Friday afternoons. Gripped by lethargy, normally productive members of the labor force will find themselves not at their work stations, but behind the wheels of automobiles heading for retreats. Thousands more will say they are going to lunch and simply disappear. Many will be found swimming off Long Island or New Jersey or on the beaches. So widespread is the summer practice in New York - more prevalent than in other cities, management experts say - that a growing number of concerns are simply giving in and closing on Friday afternoons between Memorial Day and Labor Day.

Young visitors to the Bronx Zoo this weekend can do more than stand back and watch the animals. They can venture into a burrow to see how prairie dogs live, or crawl inside a big snail shell to find out how snails get around. There is even the nest of a black-crowned night heron to climb into. The exhibitions are part of the new Children's Zoo, a three-acre tract of marsh and woodland where some 110 animals live in settings close to their natural habitats. Raccoons make their home along the bank of a stream, with their natural neighbors the black-crowned heron living close by. The zoo also contains an area for visitors to pet and feed goats, rabbits, pigs, chicks, lambs, geese and snakes to their heart's content. The Children's Zoo is open daily 10 A.M. to 4 P.M. and costs 80 cents for children, 70 cents for adults. But be warned; adults must be accompanied by a child. Information: 933-1759.

Perturbed by signs that the Federal Reserve is determined to keep a tight rein on bank reserves and the nation's money supply, the credit markets retreated yesterday, and yields rose for both shortand long-term securities. For the second consecutive day, the interest rate for overnight bank loans in the Federal funds market rose above 20 percent, which convinced many, but not all, analysts that the Fed had decided to make reserves scarcer in the financial system, a move that normally results in higher interest rates. In the Treasury bill market, three-and six-month rates rose to 17.15 percent and 16 percent, respectively, before declining slightly later in the day. Dealers said that upward pressure on Treasury bill rates might continue in the future because foreign central banks had been aggressively selling dollars to raise the value of their own currency.

ACTORS frequently talk about challenging themselves; some actors even do something about it, and when they do, it is often away from Broadway. With skyrocketing costs and the resultant increase in the timidity of producers, Off Broadway and Off Off Broadway continue to attract those actors, many of them with established reputations, who want to test their mettle and extend their range in classics as well as unusual new plays, in monologues as well as in collaborative performance pieces. Often actors head away from Broadway for reasons of necessity - specific projects may be considered questionable commercial prospects - but sometimes they do so voluntarily. Such is the case with Al Pacino, who begins previews this evening in a revival of David Mamet's ''American Buffalo'' at Circle in the Square's downtown theater (254-6330), a legendary home for memorable performances.

After receiving a report that called Roy L. Williams, interim president of the International Brotherhood of Teamsters, ''an organized crime mole,'' a Senate subcommittee recommended today that the Labor Department determine whether he was suitable for high office in the nation's largest union. The panel questioned his suitability because he declined to answer its questions last year about his alleged connections with organized crime. At the same time, law-enforcement officials said that the Government had decided to ask a grand jury to indict Mr. Williams and other union officials on charges of improperly attempting to influence Senator Howard W. Cannon, Democrat of Nevada, on a trucking deregulation bill in 1979. The report on which the Permanent Investigations Subcommittee acted said that Marty Steinberg, the panel's minority chief counsel, had reported that ''additional information received in public session was that Roy Lee Williams was an organized crime mole operating at senior levels of the teamsters' union and exercising great influence with the Central States pension fund.''