Neighbors has two things going for it: genuine laughs and Zac Efron’s abs. Seriously, that’s the dynamic the film creates. Although Seth Rogen is now firmly established in the annals of comedic history, he needs to adapt to survive. Although not old by any means at 32, he needs to move on from the slacker, stoner image he cultivated years ago. OK, he may still be a stoner, but now there’s a another generation below him and in this film they’re represented by Zac Efron and Dave Franco. Rogen plays a new father and husband who’s worried about his youth slipping away. And yet, while the film is plenty funny, it rarely comes out of this established — or perhaps under-established — dynamic.

Directed by Nicholas Stoller (Forgetting Sarah Marshall, Get Him to the Greek), the simple plot is that a frat house led by Teddy Sanders (Efron) and Pete Regazolli (Franco) move in next door to new parents Mac and Kelly Radner (Seth Rogen and Rose Byrne). Mac and Kelly are rightly worried about living next to a 24/7 party, but are somewhat intrigued and attempt to befriend the bro-crew in order to gain their respect and, therefore, their silence. But after an all nighter of booze, weed, and shrooms, Mac and Kelly have to return to their “adult” lives while Teddy and his gang can continue the good times.

Despite what they all assumed was a newfound friendship, when Teddy won’t pick up Mac’s calls during a bash in the middle of the night, he resorts to calling the cops and a feud is born. Mac and Kelly may just want a little quiet now and them, but Teddy contends that he can’t be contained in his effort to have a truly legendary party that will earn him a spot on the frat’s wall-of-fame — despite Pete later pointing out that it’s all nonsense. If Mac and Kelly are worried about their fading youth, Teddy is caught up in a serious case of arrested development.

Stoller and Co. make sure the film is not short on laughs. Whether it’s a running joke of frat brother Scoonie’s (Christopher Mintz-Plasse) enlarged member, or stolen airbags from Mac’s car that Teddy hides in his home and office, it’s never wanting for humor. There’s even enough subtle humor to drive the more expository moments, like Kelly — who’s graced with Byrne’s native Australian accent and background — not realizing that the Dean of the University, Carol Gladstone (Lisa Kudrow), isn’t actually just a woman named Dean. But, as funny as the film can be — and it really does pack in more laughs than past Stoller efforts — it begins to run out of steam even in its short running time of barely over 90 minutes.

The problem is that although the film sets up a viable war of contention, it doesn’t establish enough within the characters to carry past the humor. As great as Rogen and Byrne can be, they lack a certain chemistry because they don’t act like a couple that’s supposed to have been together since college. Instead, they lob improvised superlatives at each other and it can create an inauthenticity in their relationship. Similarly, while Teddy’s character is slowly set up as an underachiever, especially in light of his best buddy Pete’s post-college ambition, it comes much too late in the film to do much other than a late game sympathy for the aggressor.

Stoller attempts to build something under the pranks, like Mac and Kelly’s continued obsession with bringing the frat down after they’ve seemingly silenced them — which Mac’s co-worker Jimmy (Ike Barinholtz) rightly points out. But what made Rogen and his crew — which includes Stoller — such a force in comedy is that underneath their foul-mouthed jokes was a charming wit, and well rounded scripts. Neighbors somewhat lacks that insight but it’s so naturally hysterical, many won’t notice what it’s missing.

Rating: 3.5 out of 5