Surely those old gags would have gasped their last. How long can a comic repeat the same wife-ethnic-sex jokes and secure a strong laugh? If the comic is Henny Youngman, the answer is--a lifetime. "The King of the One-liners" has used the same schtick for almost 50 years--and it still works.

The advances and ads in the press for his recent University of Florida appearance were few and brief, though occasionally tagged with a boastful "Take your wife--please." Nearly 2,000 students appeared to hear his 40-minute routine; noted poets, playwrights and politicians have failed to attract so large an audience at the campus.

When the comedian finally lugged his 6-feet-2-inch frame across the gymnasium floor with his famous short-step gait, the audience immediately granted him a standing ovation.

At 74, Youngman seems to be as enduring as his jokes. His hair has thinned, his back and shoulders are perhaps more noticeably hunched, the bags beneath his eyes darker and deeper. But time hasn't altered him much. The black suit with the silk lining, the stiff bow tie: the image is intact. And so are the jokes.

"I got an offer to do a movie with Bo Derek--you know, that 10 girl." Some male members of the audience hooted and whistled. "Producer called me up. Said, 'How about $50,000?' I said, 'I'll think about it.' He called again. Said, 'We'll make it $20,000.' I said, 'I'll pay it.'

"Derek and I got dressing rooms next door to each other. I noticed there was a little hole in the wall. I thought, 'What the hell-let her look.'"

Years ago he may have used the name of Racquel Welch or Ursula Andress, but the joke would have been the same. It hasn't changed and neither has its response, an almost unified laughter that comes right on cue.

In an interview after the program, Youngman admitted his "biggest thrill is playing colleges such as this--seeing a couple thousand students come out to hear my stuff.'

From a generation that usually identifies with the humor of a George Carlin, Gabe Kaplin or Richard Pryor, Youngman extracts laughs without reference to drugs or four-letter words.

"I try to keep it clean. I don't think it has to be filthy. But it doesn't bother me when younger comics do dirty stuff. They're doing their own thing."

Youngman's style is what grants his humor a lasting quality. It's a rapid-fire technique that hasn't changed since he mastered it in the Thirties. He'd been working as a night club comic, employing a cigar instead of a violin as his prop, when he signed (without an audition) to do a six-minute spot on the Kate Smith radio show. He was an instant hit and the producer extended his routine to 10 minutes. With a $250 check in his pocket for 10 minutes of work, Youngman realized he was a sudden success. Since his time was so brief, he decided to stick to jokes that could be delivered quickly. Youngman's jokes not only had punch lines, they had punch words.

"The take my wife--please' thing started kinda by accident when I was on the Kate Smith Show. About 15 minutes before it was supposed to go on my wife can up to me with several ladies. They had tickets but she didn't. So I asked them to take my wife--please. It stuck." The wife in all those jokes is Sadie Youngman, who sold sheet music at Kresge's when they first met. They've been married 52 years.

Wife jokes have become a Henny Youngman trademark and he relied on them heavily with his college audience:

"I'm bow-legged. My wife's knock-kneed. When we stand beside each other we spell OX."

"My wife is on a diet of coconuts and bananas. She hasn't lost any weight--but can she climb trees!"