It’s his 21st birthday, and what does Jeff Chang (Justin Chon) do on his big day? He prepares for his meeting with a prestigious medical office — that is, until his high school buddies from back home make a surprise visit. When one beer at a bar turns into an insane, night of wild partying, Miller (Miles Teller) and Casey (Skylar Astin) have a lot of cleaning up to do before they can get their friend back home.

Some may be thinking that “21 and Over” is like any other party movie — drunk kids, pretty girls and nudity galore. However, writers Scott Moore and Jon Lucas’ (“The Hangover”) first stab at directing is no disappointment.

“They work insanely well together,” Astin said about his directors. “They have been writing partners for years, and when they transitioned into being directing partners it was seamless.”

Even as their directing shines, the duo’s writing is still as polished as ever. Some of it, in fact, was even ad-libbed by the actors, which makes it even more outstanding.

“There was a lot of ad-libbing. We call them ‘alts,’” Teller said. “Me and Skylar did some impromptu training, and we just worked well off of each other.”

Viewers may recall Teller from 2012’s infamous party movie, “Project X.” When asked why he is attracted to such raunchy, booze-filled party movies, Teller laughed and said, “Just the parties and the girls.”

“With ‘Project X,’ the movie is literally one big party,” Teller continued. “This is more of a journey. I was just excited to do it. And I also like to party. And I like girls.”

Teller isn’t the only familiar face. Viewers may recognize Astin from last year’s popular film “Pitch Perfect” as Anna Kendrick’s love interest, Jesse.

“Little known fact, I shot this film before ‘Pitch Perfect,’” Astin said. “It was actually a tough ride to come down from because this movie was a non-stop party. It was cool to do it back-to-back. I enjoyed both projects very much.”

Believe it or not — and this is aside from a tender, slow-motion throw-up scene on a mechanical bull — “21 and Over” has heart too, with important lessons and tangible friendship. Still, knowing that “21 and Over” is from the guys who brought audiences “The Hangover,” one might expect — and rightly so — the film to contain some graphic nudity.

“The most uncomfortable part was the hour-long work of makeup that I had to get done on my ass,” Teller said. “There was this dude powdering my butt as I was trying to talk about sports. But those nude scenes out on the quad felt kind of cleansing.”

Fans of “The Hangover” and “The Change-Up” should see “21 and Over,” and unlike the movie’s drunken main characters, you won’t forget what you’ve experienced.

A version of this article was published in the Thursday, Feb. 28 print edition. Ishan Seth is a contributing writer. Email him at [email protected].