“Beerfest,” a Warner Bros. release, is rated R for pervasive crude and sexual content, language, nudity and substance abuse. Running time: 112 minutes.

Two stars out of four.

“Beerfest” is like tapping a keg that’s had a bumpy ride to the party.

The first pints keep coming up pure foam, with so much undrinkable froth you begin to wonder why you bothered showing up.

Gradually, things settle down, you start to get an inch or two of tasty amber in the glass beneath that thick white lather.

Eventually, although the tap still sputters through the evening, you get some really nice pours, rich glasses of lager with just a crew cut of a lathered head.

The movie from the comedy troupe Broken Lizard plays out just like that: dreadful at the outset, without a laugh in sight, but slowly improving as the gang manages some genuinely funny jokes and sight gags.

Pushing two hours in length, “Beerfest” is much longer than a gross-out romp about extreme drinking games really should be.

So many of the bits fail to click that the movie could have stood 20 minutes or more of cutting in the editing room, with sharp improvement in the pacing.

Still, “Beerfest” lifts Broken Lizard back on par with its 2002 mini-hit, the cop spoof “Super Troopers,” a significant rebound after the troupe’s execrable 2004 slasher-film parody “Club Dread.”

The movie is written by and stars the five-man funny team – Jay Chandrasekhar, Erik Stolhanske, Paul Soter, Kevin Heffernan and Steve Lemme.

Director Chandrasekhar infuses loose, goofy, sketch-comedy energy through much of the movie.

He’s clearly more relaxed working with his old friends than he is as a filmmaker for hire, as he was when directing last year’s woeful “The Dukes of Hazzard.”

“Beerfest” opens with such a weak, obnoxious prologue, it’s surprising the Broken Lizard boys are able to rebound and win viewers back as well as they do.