It's a classic story repeated so often at parties and on late-night TV that it has endured for decades

Rest in Peace, Don Rickles. If there’s a heaven, I hope you’re there, giving God hell.

Rickles, who died Thursday at age 90, was the source of one of the bravest put-downs ever told, a classic story repeated so often at parties, on radio and on late-night TV that it has endured for decades.

Rickles became famous as an insult comic, sarcastically nicknamed “Mr. Warmth” for his brutal putdowns of friends and foes alike. Instead of trying to win over the audience, he made them his adversaries — and they adored him for it.

The comedian was fearless. No one was too big to mock, and one of his favorite targets was the charismatic and fearsome Frank Sinatra — the man no one teased, lest it be ring-a-ding-ding for them.

As fellow headliners in Las Vegas during the early 1960s, Rickles often found himself Rat Pack adjacent and became a favorite comic of Ol’ Blue Eyes, partly because he was one of the few willing to joke at the singer’s expense.

One time, he crossed the line, all for an audience of one. But it turned out to be Sinatra’s favorite prank of all time.

I’ll let Frank tell it …

Come on. Come on. It doesn’t get better than that.

It’d be easy to ruin the joke by dissecting it, so I’ll just acknowledge the basic fact of why it’s so funny: Rickles had balls.

The audacity of it is so staggering, you can’t help but laugh, apparently even if you’re the one who was made the laughingstock. Rickles is the little bird who hops in to poke around the teeth of the alligator, and Sinatra kindly chooses not to slam his jaws shut and devour him.

It’s a credit not only to the comedic mind of Rickles, but to the good-sport nature of Sinatra that both men love that story, and both swear it really happened.

It’s such a good story, it better have. (Although when Sinatra tells it, the prank happened in a New York restaurant, and when Rickles has told it, he says it was at the Sands Casino in Las Vegas.)

Here’s Rickles telling the tale himself decades later on The Tonight Show once again, this time to Jimmy Fallon instead of Johnny Carson.

Here’s to one of the all-time greats, who wasn’t afraid to pick on people bigger than him.