My lunch with Don Rickles, at the traditional chophouse in Beverly Hills, the Grill on the Alley, had scarcely begun when another customer bowed three times before him with his arms folded across his chest, as if addressing a sultan.

Jeffrey Katzenberg was paying homage to the legendary comedian, who is sometimes known as “The Insultan” or, more usually, “Mr. Warmth.”

“You are in the company of the genuine greatest,” Mr. Katzenberg said to me enthusiastically.

“We rehearsed this,” Don Rickles added.

But someone else soon came over. “Excuse me, Mr. Rickles. Frank McCourt.”

“I know who you are, Frank,” he said amiably to the owner of the Los Angeles Dodgers. And they schmoozed for a while, too.

“Put it this way, Mr. Rickles,” I teased him later, “who don’t you know?”

“Aaaaaw,” he responded diffidently.

This was not the Don Rickles I had anticipated. The Las Vegas entertainer who has been insulting doting audiences for half a century turned out to be a sweetheart. “The sweetest man I’ve ever known,” his closest friend, Bob Newhart, said about him, though he once told Rickles, “What I can’t figure out is how you do what you do and yet still live.”

He had a Bloody Mary before ordering a chicken burger carefully. “No fries, Steve,” he told the waiter.

“You keep fit?,” I asked.

“I ride a recumbent bike for half an hour every day. Why, do I look sick?”

“No, you look good.”

“I look better than you, John. I don’t want to lie to you, but you don’t look good.”

He beamed good-naturedly. It was a reminder.

Mr. Rickles was raised in Jackson Heights, Queens, the son of an insurance salesman. His adored mother, Etta, was an unstoppable showbiz mom whom he described for me as “the Jewish Patton.” It was Etta who organized her son’s big break, in the early 1950s, when she somehow persuaded Dolly Sinatra to get her son to see his lounge act at Murray Franklin’s, in Miami Beach.

“Make yourself comfortable, Frank,” the fearless Rickles greeted Sinatra when he walked in with his entourage. “Hit somebody.”

Sinatra and, later, Johnny Carson became his biggest fans.

“Where does your nerve come from?,” I asked.

“Well, I call myself an actor,” he replied, surprisingly. “I always wanted to be one.”

As a young man, he attended the American Academy of Dramatic Arts, in New York, along with Anne Bancroft and Jason Robards, who became a good friend. “You’re saying that you’re pretending to be Don Rickles onstage?”

“When I’m onstage, I’m acting,” he explained. “When I’m with you, I’m normal. I don’t do stand-up comedy. I don’t do jokes. I don’t come out and say, ‘Good evening, ladies and gentlemen. Two Jews got off a bus … ’ I’ve never had a written script. You know what’s funny to me? Attitude.”

Don Rickles, the last of a breed, found his unique voice when he started out as a warm-up act in strip clubs. (One of the strippers he knew was Sally Marr, mother of Lenny Bruce.) “It was a great training ground,” he remembered fondly, “because you had to improvise without ever losing your cool. You had to talk back to the guys waiting for the girls to come on, and win the audience over.”

All solo entertainers belong to a warrior class. When they succeed, they talk of having “killed”; when they bomb, they “die.” But the appealingly uncomplicated Don Rickles says he just loves what he does. Now 83, he could have long since retired with his wife of 44 happy years to their Malibu house, where, he told me with a smile, he owns “a sailboat called ‘The Couch.’” But he still performs 75 to 80 nights annually, eagerly returning most years to Las Vegas.