What was going on when I was born?

All Steven Miner wanted from the Gillette Company was what the 1978 advertisement offered - a free Accent table cigarette lighter, retail value $7.95. As required, Mr. Miner sent off 50 cents for postage and handling and proof of purchase of two of Gillette's Cricket disposable cigarette lighters. Instead of the lighter, though, Mr. Miner ended up with a Supreme Court case testing the use of nationwide consumer class-action lawsuits in state courts. As a practical matter, a ruling against Mr. Miner would go a long way toward preventing the multimillion-dollar damage awards in consumer actions. Such awards in other areas - one recent antitrust class action involved damages of more than $1 billion - have made class actions anathema to many corporations.

President Reagan said the U.S. will allow Brazil $1.2 billion in short-term loans to help it meet its debt crisis. On the first day of his Latin American trip, the President urged lenders around the world to aid indebted developing nations and he praised Brazil's austerity measures. In New York, Brazilian bank officials were seeking a $2.4 billion loan from commercial banks. (Page A1.) Mexico's new President announced sweeping austerity measures to deal with the country's economic problems, which were described as intolerable by President Miguel de la Madrid Hurtado in his inaugural address. His plan includes budget cuts, new taxes, price increases and an easing of foreign exchange controls. (A1.)

An underwriting syndicate headed by Morgan Stanley & Company yesterday sold 16.5 million shares of common stock in the American Telephone and Telegraph Company for $990 million. The entire equity offering - one of the largest in history - was snapped up by investors at the $60-a-share offering price, Morgan Stanley said. The huge offering of new shares prompted heavy trading of existing A.T.& T. stock on the New York Stock Exchange yesterday. About 1.7 million shares changed hands, and the stock closed at $60, unchanged from Tuesday's close.

New York City's Health Department announced yesterday that it had issued a permit allowing a Connecticut company to sell ''horseburgers'' and horse-steak sandwiches from pushcarts in midtown Manhattan. The company, Chevalean Foods, had its first cart on Lexington Avenue, near 53d Street, soon after the announcement and did what its president and vendor, Ronald Corn, called a ''fairly good'' business ''despite rainy weather.'' He said he had sold about 50 quarter-pound burgers and steak sandwiches, with the burgers going for 75 cents plain - 85 cents with cheese - and the steak sandwiches for $1.40. The company is based in Hartford, where Mr. Corn and Morris Later operate the M & R Packing Company. Mr. Later, the vice president, said they had been slaughtering horses for export to Europe and the Middle East for 10 years and selling sandwiches from carts in Boston, Hartford and New Haven for several months, and that, yes, they had heard lots of jokes.

With Senator Edward M. Kennedy out of the 1984 Presidential race, the chances of all other Democratic hopefuls obviously improved yesterday. But the clearest gains were not for any individual Democrats, but for organized labor. Cases were already being made for most of the active contenders for the party nomination as to how Mr. Kennedy's withdrawal had helped their particular prospects. In a larger sense, it helped them all, because the Massachusetts Democrat could have carried into the race a bigger core of support than any other contender.

Most of the nation's major airlines quietly put into effect yesterday a 5 percent increase in fares on most of their domestic routes in hopes of increasing profitability. The fare increases, which were not announced, were in sharp contrast to the highly publicized discounts on some transcontinental and New York-to-Florida fares that also went into effect this week. The discounts reduce the one-way fares on these routes to $99 for short periods before and after the Christmas holiday. The 5 percent increase, which applies to the overwhelming majority of the nation's routes, is the third across-the-board fare rise this year: In July, fares rose $10, and in September, there was a 5 percent increase. Under current deregulation rules, the airlines are able to put increases into effect after notifying the Civil Aeronautics Board.

Talks between New York City and the Yankees have broken off, and the city said yesterday that it would proceed with its lawsuit to prevent the baseball team from playing its first three scheduled home games in Denver next spring. The dispute centers on $900,000 in repairs that the city began at the stadium on Oct. 7. George M. Steinbrenner, the Yankees' principal owner, contends that the ballpark may not be ready for the team's opening game on April 11. The city said in court papers yesterday that at most, all but 2,000 of the stadium's 57,545 seats would be usable by then. Mr. Steinbrenner has said he made plans to open the season in Denver's Mile High Stadium after the city notified him by letter on July 23 that the repairs might not be finished in time. The city disputes his interpretation of the letter.

The battle for control of Chock Full o'Nuts was waged in the ballroom of a midtown Manhattan hotel yesterday, and those who think annual meetings are dull missed entertainment that often seemed more fitting for ball park bleachers or a neighborhood bar. ''You are a liar!'' one shareholder shouted at Jerry Finkelstein, a 66-year-old New York financier and political power broker, and Mr. Finkelstein returned the charge. Then his microphone went dead and he walked through the buzzing crowd of shareholders with his arms raised like a triumphant boxer. ''A pox on both your houses,'' said one woman, referring to the contending slates for the board of directors -one offered by Mr. Finkelstein and his group of 15 investors, the other by the current management, which includes William Black, the company's founder and chairman, his wife, Page, and Leon Pordy. He is the company's president and also the personal physician to Mr. Black, who is over 80.

International American loans to Brazil totaling $1.2 billion were announced by President Reagan. Amid a round of talks in Brasilia, Mr. Reagan said Washington would provide the emergency short-term loans to help Brazil overcome its huge debt problem, and he praised Brazil's leaders for taking austerity measures. (Page A1, Column 6.) Austerity moves in Mexico were announced by Miguel de la Madrid Hurtado at his swearing-in as President. His program calls for budget cuts, new taxes, price increases, postponement of public works projects, higher interest rates and eased foreign exchange controls. (A1:5-6.)

The leader of a Lebanese Phalangist Christian faction said today that the killings of Palestinian civilians in two refugee camps in September were ''a Lebanese reaction from the relatives and parents of our martyrs.'' Etienne Saqa, head of a faction called Guardians of the Cedars, which is part of the rightist Phalangist coalition in Lebanon, was asked repeatedly at a news conference sponsored by the Israeli Government whether his group participated in the killings at the Shatila and Sabra Camps. Mr. Saqa did not answer directly. The slayings at the refugee camps occurred after the assassination of President-elect Bashir Gemayel, the leader of the Phalangists, on Sept. 14. ''First of all, I want to ask you why the whole world is upset by Sabra and Shatila,'' said Mr. Saqa, who wore dark glasses to fend off the glare of television cameras. For eight years during the civil carnage in Lebanon, Mr. Saqa said, the world ''was asleep'' and ignored the killing of Christians by Palestinians in Lebanese towns such as Damur.

The Cadillac Fairview Corporation drew attention in the 1970's by putting together dramatic real estate deals that changed skylines from Calgary to California. In these less buoyant times, it is attracting even more attention through a strategy of becoming stronger by becoming smaller. In October, Cadillac forfeited a $21 million downpayment on property at Third Avenue and 53d Street in New York that it viewed as uneconomical. The property, which was to have been the site of a major office tower, had been purchased for $105 million, or an astronomical $1,900 a square foot.

THE curve is a sweeping left-hander leading onto the freeway, and Ponce Kiah Marchelle Heloise Cruse Evans deftly downshifts her chocolate brown Porsche Turbo Carrera and slips easily into the turn, steady as a rock as she whips into the outside lane, her long silver hair rippling in the wind. She likes to drive, she acknowledges, conceding the obvious. The license plate on the Porsche reads HOT AER, because she also pilots a hot-air balloon. She is lithe, 31 years old, married 18 months, rides a motorcycle and blow-dries ferrets. Not quite the image you would expect of the woman The New Yorker called ''the premiere household-hints columnist of all times,'' the helpful-hint maker millions of homemakers know simply as Heloise.