Some teens go off to college to realize their dreams. Green Day hit the road in a bookmobile.

Before turning 20, the members of the iconic Bay Area punk trio – Billie Joe Armstrong, Mike Dirnt and Tré Cool – toured the world leading up to their breakthrough success with the 1994 album “Dookie.” Episodes from that nomadic life are woven into the coming-of-age narrative of “Nimrods” (in theaters Aug. 14).

“You always have that teenage heart, even though we’re middle-aged men. It’s important to kind of have that feeling, the vitality and the youth of it,” says Armstrong, 54.

In writer/director Lee Kirk’s music comedy, Mason Thames, Kylr Coffman and Ryan Foust play Kansas City kids who get a call that their band, the Analog Dogs, has been invited to open for Green Day’s New Year’s Eve show in LA – not knowing it’s a prank. The youngsters head out on a journey full of friendship, love, rocking tunes and bad puns.

The latter come courtesy of Gravy, a puppet Dirnt used back in the day to entertain his pals on the road that inspired a cinematic counterpart. “He would have been really happy with the performance of the actor Gravy,” Dirnt, 54, jokes.

Armstrong wanted to make a Green Day-inspired movie, but although the band would appear, it was important that it be “someone else’s story.” The Green Day frontman reached out to Kirk – who cast Armstrong as an aging rocker in 2016’s “Ordinary World” – and Kirk listened to them tell tales from the road until he had “enough nuggets of stuff” for a screenplay, the director says.

Green Day discusses real-life incidents that get the Hollywood treatment in “Nimrods”:

Like Billie Joe Armstrong, the main character in ‘Nimrods’ lost his dad in childhood

Though the movie parents aren’t exactly pleased when they find out their kids are traveling across the country, Green Day’s were all for it. Dirnt recalls his mom being “super-supportive” of them touring as teens, and Cool’s dad would drive the trio around in a refurbished bookmobile in the early days – which inspired the Analog Dogs touring in an ice cream truck. Armstrong’s 94-year-old mother, Ollie, still comes to Green Day gigs. “We used to rehearse in the living room while she was making spaghetti,” Armstrong says. “She loved it.”

The personal life of Thames’ character, Tommy, was inspired by Armstrong’s, including the emotional impact of having a musical father who died when he was a kid. While “Tommy’s not supposed to be Billie Joe,” Kirk says, “that really informed the movie, being about a family dealing with a crisis and coming back together.”

Green Day and the Analog Dogs both played to less-than-adoring crowds

Needing money on the road, the Analog Dogs stop at a country bar, sign up for a battle of the bands, and win over an initially skeptical crowd to take the victory. Though they didn’t have any weird moments at musical competitions, Armstrong recalls playing a nearly hourlong show at Foreign Foods Day in 1990 at their high school. (There are YouTube clips for those needing to see a very green Green Day.)

“I thought it was an incredible performance, but there’s nobody watching us except for a couple of our friends,” Armstrong remembers. “That was kind of funny.”

Tommy finds love on the road, just like Billie Joe Armstrong

Heading to LA, Tommy runs into a fellow rocker named Olivia (Mckenna Grace) during a convenience-store stop, and sparks fly. That subplot was inspired by Armstrong meeting his future wife, Adrienne, in 1990 while rolling through Minneapolis during Green Day’s first tour.

Their meet-cute moment? “I was shooting bottle rockets at her,” Armstrong confesses. A day after seeing Green Day play in a basement, she came up to Armstrong at the music club that was the band’s next stop and inquired about buying records for her as well as her friends in England. “We became pen pals; then she came out to California in 1991, and we got married in 1994. We’ve been together ever since.”

Green Day’s infamous 1994 Woodstock appearance sparks ‘Nimrods’ mud fight

The Analog Dogs’ trip west includes a stop where they play for a bunch of youngsters at an outdoor junkyard; when a rainstorm rolls in during their set, a joyful mud fight breaks out. In that are shades of Woodstock 1994, where Green Day and the crowd flung mud at each other, and Dirnt wound up getting his front teeth knocked out by a security guard who mistook him for a fan. “Better me than some kid in the crowd,” Dirnt says. “At the end of the day, we had a great time. If you’ve got to take one on the chin to be awesome in history, go ahead.”

In the moment, Cool, 53, was enjoying himself because “I was safely out of reach” of incoming mud balls behind the drum kit, he recalls. “I loved every minute of it until I saw this giant man on top of Mike.” Adds Armstrong: “When Mike got tackled, I jumped on top of the bouncer’s head. I looked like Bugs Bunny as the Masked Marauder or something. And so I was punching that guy in the head. It was just nuts.”

In person and on-screen, Green Day makes its fans famous

A Green Day concert is a major plot setting in “Nimrods,” and in the movie, the band brings an excited fan onstage to play with them. That has been an actual band tradition since the mid-1990s, though audience participation has been a thing ever since Green Day’s beginning. “Some places we’d play, half the audience would be onstage holding the microphone so I don’t get kicked in the mouth from the moshing going on,” Armstrong says.

While in New Orleans on the “Insomniac” tour in 1996, Armstrong recalls being in “a bit of a mood” while playing the Operation Ivy song “Knowledge.” “I said, ‘Anybody out there want to play this thing?’ I just grabbed a kid out of the crowd, he put my guitar on, I showed him the three chords, and then this thing happened where everybody was involved in the show. It just kind of broke the barrier between us and the audience.”