It was a rare case of “out of the fire and into the Friars.”

Jimmy Fallon apologized to his staff this week after a Rolling Stone exposé claimed that he’d created a toxic environment at the 30 Rock HQ of his “Tonight Show with Jimmy Fallon” — in part because he seemed to have shown up to the office smelling of booze back in 2017.

But Page Six has heard over the years that Fallon, 48 — who had a legendary reputation for drinking, and occasionally getting into high-spirited scrapes, at downtown watering holes including Niagara, and especially the long-defunct Siberia — used the private Friars Club as a safe space for the gregarious host to let his hair down without making the gossip pages.

While the struggling 55th Street club is famed for its celebrity members — who, generally speaking, happily drank among the other members at the various bars around its clubhouse — we’re told Fallon was often ensconced in rooms that were especially closed off from other card-carrying folks, with his writing staff as party pals.

As this reporter once discovered the hard way, anyone not in the NBC fold was told to take a hike.

In fact, it was much speculated around the hallowed halls once walked by Frank Sintra and Jerry Lewis, that NBC brass were the ones who came up with the Jimmy management strategy.

But on Friday an NBC spokesperson told Page Six that was not true. A spokesperson for Fallon declined to comment.

A Friars’ insider told us, “He did bring his writers to the club and they’d have a private room, but I don’t know if that was organic, as he’d hang out there anyway — he gifted the writers annual memberships so it makes sense that’s where they’d hang —or if NBC encouraged it. Could have been a win-win for both.”

Fallon is under fire after a Rolling Stone article quoted 16 current and former employees accused him of being erratic, drunk at work and “creating a toxic work environment.”

“Nobody told Jimmy, ‘No,’” a staffer told the magazine.

“Everybody walked on eggshells, especially showrunners,” another former employee said.

“You never knew which Jimmy we were going to get and when he was going to throw a hissy fit. Look how many showrunners went so quickly. We know they didn’t last long.”

Fallon offered an apology to “Tonight Show” in a Thursday night video call.

An attendee of the all-hands meeting characterized the funnyman’s mea culpa as “pretty earnest.”

“It’s embarrassing, and I feel so bad,” Fallon allegedly said. “Sorry if I embarrassed you and your family and friends . . . I feel so bad I can’t even tell you.”

Fallon made headlines in 2014, shortly after he got the “Tonight Show” gig, for getting caught up in a scuffle at East Village bar Niagara, and we’re told the alleged retreat behind Friars lines happened shortly after.

But the Friar’s Club closed this past spring — so where will the funnyman hide out now?