"If I had know I was going to live so long," 102-year-old George Gant quipped to his hosts yesterday, "I would have taken better care of myself."

Later, Gant, who lives in Northwest Washington with his blind sister and who walks one mile every day to stay fit, got a bit emotional when asked about yesterday's party--a special celebration with about 30 guests, each of them at least 90 years old. "It's so swell, I can't hardly tell you," he said. "It's nice when people remember us old folks."

Washington restaurant owner Sam Lipowsky said he first got the idea two years ago while driving along Rock Creek Parkway. "I was thinking about old people and how in this country we treat 'em so lousy, like rocks along the parkway," the 55-year-old Lipowsky explained yesterday. "We just throw 'em out in the cold. It ain't right. I wanted to do something."

So Lipowsky, who never knew his own grandparents, went home, talked it over with his 24-year-old son Mark, who had worked in a local nursing home, and together they decided to throw a big bash for Washington's oldest citizens to celebrate the New Year.

Yesterday, the Lipowskys opened their family-run restaurant, Mr. L's at 5018 Connecticut Ave. NW, to the elderly revelers for the second year in a row. There were paper streamers, shiny party hats, a special decorated cake, dinner of turkey with dressing and bottles of sparkling bubbly awaiting the partygoers, many of whom were confined to wheelchairs.

There also was a mob of reporters, including two national television crews, who crowded between folding chairs and whose bright lights threw a spotlight, at least for a few moments, not only on the grinning Liposwkys but on their guests as well.

"This is so wonderful," said 93-year-old Mary Sellman, glancing around the room like a young girl attending her first party. "It's just so nice."

"Tell them when was the last time you were out of the nursing home," Donna Tompkins, a social worker with Sellman, prodded.

"I haven't been anywhere since last year's party right here," Sellman replied. "I sat right over there. It's just so wonderful to come back."

For many, including 88-year-old Brooks John, who said he was a vaudeville performer during the early 1920s, the party was a time for memories and laughter. Playing a banjo, John sprinkled the old tune that goes, "I wanna girl just like the girl that married dear old dad," with chatter about how he has been married for 56 years and now has his own built-in audience: six children, 16 grandchildren and eight great-grandchildren.

"This is an excellent idea," said Ann Groves, activities director at a Silver Spring nursing home that sent Jorgen Kjell, who explained to reporters that he was "94 and one-half and still holding." He added, "So many of these people have lost their relatives. Getting out really peps them up."

There were nearly as many reporters as elderly and there was a special press table loaded with sandwiches and cookies, but both Lipowskys bristled at the suggestion that they could be seeking publicity through the party. "People can think what they want," said Sam Lipowsky, "but when a man who is 95 or 98 clutches your hand with his trembling hand and says 'God Bless You'--you really don't care what other people might say."

The partygoers seemed to enjoy the attention. Lifting a glass of champagne in front of television cameras, one bald guest announced that one of the secrets of long life was avoiding all alcohol. Then he drank his glass dry.