Boogie days (Image via MGM)

To make a good movie, write what you know. To make a great movie, write what someone else knows and tease out the winning aspects that person might never see as clearly.

Licorice Pizza, Paul Thomas Anderson's eighth feature, takes place in 1973, just three years after Anderson's birth. Yet — inspired by the stories of producer and former child actor Gary Goetzman — it unfurls with breathless authenticity, as if it could only be the filmmaker's own teenage diary.

In a way, the film is like its title, which is taken from a '60s-'80s Glendale record store; it is a reference you have to either know or figure out on your own, and nowhere in its namesake does Anderson waste time explaining any of the simultaneously larger-than-life and nostalgically familiar goings-on. It's so much better this way. Licorice Pizza rolls over you like a sudden memory so powerful you're annoyed when you realize you're here and not there.

It's also the most unexpectedly funny movie of the year.

Disaffected nice Jewish girl Alana Kane (singer Alana Haim, in a starmaking debut) is working as a photographer's assistant during a high school picture day when 15-year-old Gary Valentine (the late Philip Seymour Hoffman's son Cooper Hoffman, ditto) puts the moves on her, boldly asking for a date. Though she makes clear it isn't a date — she is, after all, at least 25 — she shows up to his preferred eatery, the hopelessly hip Encino joint Tail o' the Cock.

Theirs is an eyebrow-raising age-gap romance in 2021, but also a reminder that teenagers often fell for young adults back then. (Check out any issue of Tiger Beat and calculate the ages of the pinup subjects.) It's clear why Gary would unashamedly wanna see Alana's boobs, but what does Alana get out of their complicated, often tense, quasi-courtship? She doesn't want to examine it too closely, and her domineering nature helps us forget about why it is ill-advised from time to time, too.

Plotless, Licorice Pizza instead settles into a pattern of introducing vignettes that push Alana and Gary's relationship in different directions, ultimately forward, dazzling with unexpected interludes that include peeks at Gary's day job as an actor, Alana's attempts to break into the business (please give the Oscar to Harriet Sansom Harris as a bonkers casting agent — she's barely in the film, but is its Beatrice Straight-man when it comes to making the most of each frame), Gary's relentless efforts at being an entrepreneur (how much more '70s does it get than selling water beds and running a pinball arcade?) and truly hysterical interludes involving Alana's sister-packed household.

Cheekily, and not unlike Tarantino's Once Upon a Time ... in Hollywood, the film winks at us via several real/fake celebrity references, doing so with inexplicably spotty discretion. For example, Christine Ebersole slays as Lucille Ball, er, Lucy Doolittle in a cameo, yet any camouflaging of who she is supposed to be flies out the window when a reference to her fictional film Under One Roof (in which Gary plays one of her 18 kids) is obscured by a full-on musical performance of the real-life theme from the real-life Ball film Yours, Mine & Ours. Sean Penn oozes slimy, booze-fueled Hollywood bravado as an obvious William Holden figure who has designs on Alana, but his character is named Jack Holden and references a war picture he made with Grace Kelly — which William actually did.

Most bizarrely, after these barely pseudonymous celebrity characters have made their mark, Bradley Cooper shows up playing Jon Peters — by name — ranting about his life with Barbra Streisand, threatening murder and putting the make on everything in a skirt.

The mixture of reality and fantasy feels intentional, and Anderson allows them to ebb and flow like a talented chef knowingly adding pinches of this and dashes of that — nothing written down.

But even though there are countless funny and well-observed flashbacks and details you'll want to Google to verify, the film is powered by its leads, who are utterly real, Hoffman shiny-faced and charming, Haim bratty yet vulnerable, easily swayed by the compliments of men both older and younger than she.

Their chemistry is dizzyingly irresistible, as is their mutual attraction to suburban danger. My God, there is a backwards driving sequence more suspenseful than French Connection.

The film comes to a head when Alana decides she needs to spend less time with silly 15-year-olds and more time getting her shit together, which drives her to volunteer in the campaign to elect Councilman Joel Wachs (Benny Safdie) mayor. Immediately thrust into a love triangle, it dawns on a disenchanted Alana that grown-up life doesn't thrill her, and she finds herself missing her goofy suitor, the one who seems to make everything exciting, the one who reminds her that she has the capacity to be as cool as she pretends to be.

As confidently cute as A Christmas Story and cheerfully problematic, Licorice Pizza is a blast.

Licorice Pizza is in limited release in theaters today, and goes wide in a month.