Don Rickles — the Merchant of Venom, the Insult King from Queens — held his tongue for nobody, not even Frank Sinatra.

As the story goes, a relatively unknown Rickles found himself performing to an audience in Miami that included Sinatra in 1957. Rickles, who died Thursday at 90, said it was his mother Etta’s doing. She met Sinatra’s mother Dolly and had her persuade the singer to attend.

The singer’s voice may have been smooth, but his temperament was reportedly anything but.

“Sinatra’s character flaw isn’t hard to name. He lived in daily fear of humiliation, and in its (often imagined) presence his temper tipped over in an instant,” Adam Gopnik wrote in the New Yorker. Furthermore, “Sinatra beat people up, or had others beat them up for him, often in shameful acts of bullying.”

Rickles, meanwhile, was an insult comic. So he took a swing at that very character flaw.

“Hey, Frank, make yourself at home,” Rickles said, before boldly adding, “Hit somebody!”

“Everyone looked to see what Frank would do,” John Landis, who directed a documentary about Rickles, told The Washington Post. “Because there were those 12 guys over there with guns.”

“If he didn’t laugh, I’d be on the Jerry Lewis telethon,” Rickles recalled to The Post years later.

Rickles didn’t, of course, become relegated to telethons. Nor did anyone shoot, hit or otherwise injure the man for his quip. Instead, his career flourished along with a long and abiding friendship with Ol’ Blue Eyes — at least according to Rickles.

His stories about his closeness with Sinatra — such as the fact that it was Sinatra who persuaded Rickles, a lifelong Democrat, to perform at President Ronald Reagan’s second inauguration during which he asked, “Is this too fast, Ronnie?” — could well be fictional.

Heck, all of his stories could easily be apocryphal. One never can tell with a comedian like Rickles, who outright admitted to fabricating stories (at least about his wife) for laughs in his autobiography, “Rickles’ Book, A Memoir.”

What is clear is that the two formed a sort of show business partnership, boosting each other’s profiles. Rickles gave Sinatra a sense of humor, and Sinatra gave Rickles an exclusive punching bag — no one else, after all, dared go after the singer.

Given that the two were both headlining in Vegas during the early 1960s — and even sometimes shared a bill — there was certainly space for crossover.

First, there were the stories, told again and again, on talk shows and interviews.

In the most popular one, Rickles found himself in Vegas with a girl.

“She wasn’t anybody I would bring home to my mother, but I really wanted to score big,” he told Vanity Fair. “And my date says, ‘My God, there’s Frank Sinatra! Do you know him?’”

Rickles told her Sinatra was a friend, “which he was. But I made it sound like my whole life.”

She didn’t believe him, so he walked over and asked Sinatra to do him a favor and come over to the table. A few minutes later, Sinatra walked up and greeted Rickles, who looked up at the superstar and said, “Not now, Frank. Can’t you see I’m with somebody?” (When Sinatra later told the story to Johnny Carson, the venue had changed to a New York restaurant — which might hint at the story’s truthfulness or lack thereof.)

Master of the comic insult, Don Rickles, has died at 90. Here's a look back at his career and legendary friendship with Frank Sinatra. (Nicki DeMarco/The Washington Post)

In another, as he recounted in his book, Rickles was in the midst of a performance at the Casbah Lounge at Las Vegas’s Sahara Hotel, when two police officers appeared on stage.

“Mr. Rickles,” the first trooper said. “You’ll have to come with us.”

Shock rippled through the audience. “They don’t know what the hell is happening,” wrote Rickles. “Neither do I.” The police brought him outside and placed him in a police car, which brought him to the Sands Hotel, where Sinatra performed.

That’s when he found out Sinatra simply wanted to spend the evening drinking with him and didn’t have the patience to wait until he finished the set.

Throughout the 1970s, the pair often appeared on late night television together and told these stories. The best of these appearances began with Sinatra speaking to Johnny Carson about what music he puts on when in the mood for romance (surely not himself). After a few moments, Rickles burst onto the stage (purportedly a surprise), walked up to Sinatra and kissed his hand.

Rickles began speaking faux Italian and making Mafia jokes — something Sinatra did not generally take lightly. But the singer spent most of the segment in stitches, until Rickles grabbed his face and gave him a big kiss on the lips. Then another.

Somehow, Rickles got away with it. He always did. On “The Dean Martin Celebrity Roast,” in front of an impressive audience that included Ronald Reagan, Dean Martin, Orson Welles, Peter Falk and many others, Rickles essentially told Sinatra his career was over. Then, he kissed him on the mouth several more times. These smooches lasted a good while.

“We do not dance together,” Rickles concluded his speech. “We do not break bread every day together. But when I’m in his company — Dean knows this and you know this — I speak of him with love. And I tell ya, we have been blessed to have such a man.”

“Frank was the kind of guy, there was no gray area,” Rickles told The Post years later. “He either loved you or fuggedaboutit.”

Regardless if any of their stories were true, there did seem to exist a true respect between the two men. Sinatra, for example, threw parties for Rickles’s wedding anniversaries. And, as Rickles wrote:

In the eighties, we became even closer. When Frank married his Barbara, he finally found a stable domestic life. They loved entertaining and were fabulous hosts. We loved when we were invited to their place in Palm Springs for the weekend. Everyone called it the Compound.

Finally, when Ol’ Blue Eyes died in 1998, Rickles served as one of his pallbearers.

Until his life ended Thursday, the comedian spoke warmly about Sinatra.

“He was the most charming, terrific man in the world,” Rickles, unprompted, told Jimmy Fallon in 2015 in a rare moment of sincerity. “He really was. He was fun to be with.”

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