If when you hear the words “Pal Joey,” you think fondly of your friend Joseph, Richard Linklater’s new film “Blue Moon” might leave you bothered and bewildered.

As for Broadway buffs and lovers of old New York, the witty, hilarious and haunting movie starring a totally transformed Ethan Hawke as musical-theater lyricist Lorenz Hart will have them utterly bewitched.

“Do you ever think of your entire life as a play?” Bobby Cannavale’s all-ears Sardi’s bartender asks Hart, who wrote “Pal Joey,” “Babes in Arms” and “The Boys from Syracuse” with Richard Rodgers, and is doing his darndest to not pound down whisky.

Good question. Richard Linklater has directed “Blue Moon,” from a stunningly smart screenplay by Robert Kaplow, almost as if it is one. 

The movie ventures to just a few places: the seats of a theater, the bar at Sardi’s, its dining room and coat room. Sharp, clever monologues abound. There’s a piano player. It would make a fantastic play.

Staginess on screen usually annoys me. Not so here. Not only is the subject matter an ideal fit for the cheat-out approach. But if you’ve ever encountered a theater vet on a barstool — full of juicy behind-the-curtain stories, catty jokes and, as the night goes on, inevitable sadness — you know they’re always performing for a packed house. 

Even when nobody else is there.

It’s just Hart and his barman at Sardi’s on the March 1943 opening night of “Oklahoma!,” the first musical his former collaborator has written without him. He ducked out early, claiming to have hated it.

“Any title that feels the need for an exclamation point, you need to steer clear of,” pretentious Hart snipes.

There’s also a prophetic, nervous sense that his career — and life — are coming to a close. He has a drinking problem, and “Oklahoma!,” much to his chagrin, is an obvious smash. Rodgers and Hammerstein become enduring household names. Hart, meanwhile, would die of pneumonia seven months later at age 48, after being found drunk and shivering outside a bar on 8th Ave.

“I’ve written a handful of words that are going to cheat death,” he says, praying it’s true.

“Blue Moon” brilliantly imagines that frustrating night, before and after the “Oklahoma!” party arrives at Sardi’s. Hart hurls insults, tells outrageous tales, hits on anyone with legs and begs his former partner Rodgers (Andrew Scott, anchored and sophisticated) to work with him again.

He’s transfixing and pathetic.

And — you could’ve fooled me — he’s Ethan Hawke. Yes, Hawke looks nothing like himself thanks to prosthetics to create a receding hairline, makeup and scenery that makes him appear just five feet tall. However, it’s just as much his extreme shift to a flamboyant attitude, nasal voice and neurotic manner leaves him completely unrecognizable. 

The add-ons don’t get in the way of the character’s humanity and Hawke doesn’t showboat, even when Hart does. It’s a tricky balance that the actor nails.

Not needing to transform much at all is Cannavale, who is unsurprisingly perfect as a 1940s Midtown bartender. 

Just one section of the movie gets windy. Margaret Qualley plays Elizabeth Weiland, a young Yale student Hart was enamored with and charmingly then creepily slobbers over. She regales him with a naughty-ish story, it would seem, to give a desperate man a thrill. It’s oddly sweet, and Qualley is very good. Everybody sparks with Hawke actually. The speech is just too long.

That’s just one small bump in an otherwise pleasurable ride that’s intellectually intoxicating and alcoholically intoxicated.

Broadway figures aren’t explored much onscreen. “West Side Story” composer Leonard Bernstein recently was in Bradley Cooper’s awful “Maestro,” but that film conveniently forgot to express what made the man such an ingenious artist. 

No part of Hart is eclipsed in “Blue Moon”: His jealousy, charisma, woe, longing and impeccable flair for words. 

It’s both enlightening and hard to believe that the creative Broadway minds who make us howl with laughter, openly cry and leap to our feet could be spending entire nights sitting by themselves, wallowing in depression at a watering hole. 

But it’s Hart’s lyrics to the classic song “Blue Moon” that speak the loudest: “You saw me standing alone, without a dream in my heart, without a love of my own.”