“Neighbors” is an “Animal House” for “The Hangover” era, a frat boy comedy that pushes the rude and raunchy envelope into daring and dirty new territory. Hilariously coarse, reasonably shrewd and clumsily sentimental, there’s no reason it won’t earn a billion and inspire a whole new generation of party hearty “bros” to go Greek when they go to college.

The hook here is not just the appeal of this band of brothers — drinking, dope-smoking, hard-living loverboys — to their peers. They’re also the sorts of guys Mac and Kelly used to be and wish they still were.

But Mac (Seth Rogen) has a office job that is pure drudgery. Kelly (Rose Byrne) is staying at home with Stella, their newborn. They have to lie to convince themselves that the obvious hasn’t come true.

“Just because we have a house and a baby doesn’t mean we’re old people.”

They strain to keep their old lives– sharing the occasional joint, spontaneous sex (in front of the baby), club hopping.

“We can have fun AND a baby! Baby’s first Rave!”

The trouble is, they can’t. And having the up-all-night kids of Delta Psi Beta move in next door just rubs their noses in it.

The kids, led by Teddy (Zac Efron) and Pete (Dave Franco), may feign neighborliness and high fraternity ideals.

“Chivalry above self!”

But they’re hedonistic beasts, living to make their legends with a fraternity that claims it invented the toga party, beer pong and the like. Telling them to “Keep it down” will never work.

And despite the “invite the old people in” flattery, despite Mac’s taste for the magic mushrooms, booze and other substances the Deltas have in mass quantities, this means war.

The random laughs are sprinkled throughout this Rogenesque comedy — the shock value profanity that the parents use in front of the toddler, the college dean (Lisa Kudrow) who will only do something about the fraternity’s behavior when they make “headlines.”

I love the stuff about the older couple straining to still seem “cool” to these kids who have no regard for anybody who isn’t at their frat house, partying like it’s 1979. The fun is supposed to build from the elaborate plots the marrieds and the bros engage in to foil each other. Only, it doesn’t.

Whoever the screenwriters, the Judd Apatow-trained Rogen makes sure there are a dizzying array of killer one-liners, such as Mac’s reaction to the first time he sees Teddy shirtless.

“He’s like something a gay guy designed in a laboratory!”

Byrne, as she proved in “Bridesmaids” and REALLY proved in “Get Him to the Greek,” can hang with the bad boys in terms of laying it all out there and cursing like a sailor.

But for such a short comedy, “Neighbors” drags. Director Nicholas Stoller (“Get Him to the Greek”) creates little momentum between the schemes and counter-schemes. Peripheral characters, while funny, show up and stop the action. Some of the “I love you, man” riffs between the bros are meant to be funny because they go on forever.

The outrageous stunts and boundaries-pushing gags are as riotously funny as anything in any “Hangover” movie. And telling this story from both the frat brothers’ and the indignant nearly-adults next door’s point of view broadens the appeal. Yeah, we used to be like that. In our dreams.

But in between the belly laughs, “Neighbors” feels like a pulled punch, a mean comedy with a soft streak, a “Hangover” that never delivers the buzz.

MPAA Rating: R for pervasive language, strong crude and sexual content, graphic nudity, and drug use throughout

Cast: Seth Rogen, Rose Byrne, Zac Efron, Dave Franco, Christopher Mintz-Plasse, Lisa Kudrow

Credits: Directed by Nicholas Stoller, screenplay by Andrew J. Cohen, Brendan O’Brien. A Universal release.

Running time: 1:36