Oh, for those innocent days of yore, when “The Hangover” was a malady and not a movie, when the words “Zach Galifianakis” were as alien as “Klaatu barada nikto.”

It seems like millennia since the binge comedy became the new normal. But here comes “21 and Over,” taking rude to a new level of crude, a post-racial romp through one epic night on one Asian-American collegian’s 21st birthday.

A couple of “Hangover” writers co-wrote and directed this sometimes inspired, often funny and occasionally psychotic pub crawl through the long dark night of Jeff Chang’s soul. Scott Moore and Jon Lucas hope we know that it’s not “ripping off” if you’re ripping yourself off.

Jeff Chang (Justin Chon from “Twilight”) is a catchphrase, a punchline and a punching bag, all in one.

As in “Just one beer, Jeff Chang.” And “Jeff Chang is a grown man and he made his own decisions.” And “I think we killed Jeff Chang.”

He’s the Ken Jeong character here, a wild-partying break from Asian stereotypes. All he may want to do is sleep in the night before a big internship interview. But his gonzo pal Miller (Miles Teller of “Project X”) and more responsible friend Casey (Skylar Astin of “Pitch Perfect”) want to get him blind drunk.

All they have to do is get him back to his apartment, sober and cleaned up by the time the kid’s comically stern dad (Francois Chau) shows up. Which we guess, from the film’s opening scene, they won’t manage.

Because Miller and Casey are naked and branded, stalking across campus in the early morning light, muttering “This never happened” when we first meet them.

The night starts with beer, with Casey falling for Jeff Chang’s gal pal Nicole (Sarah Wright), and it staggers to a sorority house and a pep rally, from a progressive dorm drinking party concocted to resemble a multi-level video game (drink and compete your way to the roof) to the campus police station and infirmary.

Jeff Chang is passed out. Miller and Casey don’t remember his address. The night is their quest to get this student in a stupor back home, as Jeff Chang incoherently blurts out random needs like “Count Chocula.”

Lucas and Moore swap the homophobic riffs of “The Hangover” for comical jabs at race — stumbling into a Latina sorority, a minefield of Asian jokes and the odd Jew jab.

The dizzying drinking montage of how hapless Jeff Chang got into his stoned state is hilarious, cleverly cut and packed with “Oh no he didn’t” moments.

“21 and Over” becomes a drag when a gun shows up, when Jeff Chang’s dark secret and Miller’s embarrassing revelation come out, when the drunken driving sight gag arrives.

But the bottom line on this bottom-baring/bottom-branding farce is “Is it funny, on top of all the shocks?” And yes, it is. On a number of few occasions, all of them involving Jeff Chang.