Every few years, something so jarring, so very traumatizing occurs that it shakes a wide swath of America to its very core and causes many of us to re-evaluate everything we thought we knew about the world.

It happens whenever we’re forced to begrudgingly respect some formerly eyeroll-inducing piece of teen-friendly man candy.

We went through this with Justin Timberlake on Saturday Night Live and again with Channing Tatum in 21 Jump Street and Magic Mike — at least among those straight guys who’ll admit to having seen Magic Mike.

Now, it’s Zac Efron’s turn after his dark, funny, multilayered role as the fraternity president who dislikes studying and shirts in equal measure in the raunchy comedy Neighbors.

Mac (Seth Rogen) and Kelly Radner (Rose Byrne) are not quite ready to be grown-ups. Sure, they have a new house and a new baby, but they still want to party — even though they’re usually so tired, they fall asleep before they can make it out the door.

Mac still sneaks out of work to smoke up, but even he’s horrified by the sight of the Delta Psi Beta fraternity moving next door to them in the nondescript city of Ardendale, aka The Town Zoning Laws Forgot.

Led by Teddy (Efron) and his vice president, Pete (Dave Franco), the members of Delta Psi accidentally burned down their last house. But the increased scrutiny isn’t stopping Teddy’s senior-year quest to throw a party so epic, he’ll earn a place on the fraternity’s wall of fame alongside past brothers credited with inventing the toga party, beer pong and the boot and rally.

During an impromptu invite to a Delta Psi party, though, Kelly bonds with the girls, and a ’shroom-tripping Mac manages to find common ground with Teddy, debating which generation’s Batman, Keaton or Bale, was better. The two seal their newfound friendship while crossing streams as they urinate into a backyard fountain.

But when another party goes on too late, Mac and Kelly call the police, and Teddy declares war on the couple.

Air bags are stolen. Bushes are trimmed into obscene topiaries. Mac and Teddy engage in a glow-in-the-dark dance battle and a sex-toy fight. And Mac and Kelly’s baby girl chews on a condom.

For such a rude comedy, there are some impressively clever bits. Even though it’s all over the trailers, Delta Psi’s misguided Robert De Niro party still kills me, especially Pete with his face hilariously scrunched up as Fockers De Niro, and the guy who doesn’t know the difference between De Niro and Pacino who wanders around yelling "Hoo-ah!"

There are no clear bad guys in Neighbors. Teddy acts out because he feels betrayed by Mac’s involving the police. And once things settle down, Mac and Kelly ramp things up to get Delta Psi shut down for good.

Given its outrageousness, Neighbors — written by longtime Rogen pals Brendan O’Brien and Andrew Jay Cohen, and directed by Forgetting Sarah Marshall’s Nicholas Stoller — feels more grounded than many of Rogen’s recent starring vehicles. "This Is the End," for example, is one of the funniest things I’ve seen in a while, but it was just bonkers.

As Mac and Kelly’s friends Jimmy and Paula, Ike Barinholtz and Carla Gallo play things a little too broad. And Lisa Kudrow, portraying the university’s dean, seems to be acting in an entirely different movie.

But mostly, the characters feel like real people. Exaggerated, sure, but real people. Teddy wants to leave his mark during what even he seems to realize will be the best year of his life. And, like many people their age, Mac and Kelly struggle to still seem hip — or whatever the kids are calling it these days — while wanting someplace safe for their daughter to grow up that doesn’t involve her chewing on stray condoms.

Rogen matures a bit as Mac, and as Kelly, Byrne once again proves she’s up for just about anything.

Neighbors, though, should be a game changer for Efron as he continues his evolution from the trappings of Disney’s High School Musical. He was good in The Paperboy, but the only thing most people remember about his role was that he got peed on by Nicole Kidman. His performance here may finally convince the skeptics who are predisposed to hate him on sight.

After all, as Mac declares, "He looks like something a gay guy designed in a laboratory."

It just proves the old adage: You can’t judge a Tiger Beat cover boy by his abs.

Just, please, Lord, don’t let Justin Bieber turn out to have been blessed with impeccable comic timing. I don’t know that I could live in a world where I have to say nice things about him.

(Christopher Lawrence reviews movies for the Las Vegas Review-Journal. Contact him at clawrence@reviewjournal.com)