Entertainment

Sweet, sick tween

Dante had Virgil to guide him through hell, but when it comes to the collection of bloodcurdling humilia tions and rage-inducing in justices known as seventh grade, we’ll just have to make do with Greg Heffley as the titular autobiographer in “Diary of a Wimpy Kid: Rodrick Rules.”

Last year’s original was a surprise hit, turning Jeff Kinney’s popular series of kids’ books into a bouncy screen version that seemed born in wry memories filtered through fond reminiscences like those in “A Christmas Story” or “The Wonder Years.” Example: a cursed piece of Swiss cheese lay untouched and moldering on the playground for so long that a mythology sprang up around it. Anyone who touched it (or even touched anyone who touched it) carried the terrible burden of the “Cheese Touch” until he could pass it along to the next doomed soul.

This time out, the name of the game is contrived physical comedy and gross-out gags — eating pizza that, unbeknownst to the diner, was discarded by others at the rubbish bin, or sitting on a melted candy bar in the car on the way to church. The latter leads to unfair charges of poopy pants.

Seventh-graders are far cooler and more anarchic than depicted in this often-dopey movie, which is aimed at more of a fourth-grade sensibility. Greg (Zachary Gordon) and his late-teen brother Rodrick (Devon Bostick, a slightly more interesting new version of Jimmy Fallon) get an opportunity when their parents leave the house, so they throw a big party. At which toilet paper gets strewn around and kids wildly drink Cokes.

So there isn’t much to this party, but concealing its existence from the boys’ parents forms the bulk of the film, which is even more episodic and scattershot than the first one. Greg’s best friend, the pudgy redhead Rowley (Robert Capron), was more developed the first time around, with his wide-eyed, unself-conscious goofiness frequently achieving surprise social victories while the squirming and neurotic Greg frets about his status in the pack.

This time Rowley is largely in the background, though he does a climactic, unintentionally funny magic act at a talent show. In the first “Wimpy Kid,” Rowley became a legend by busting out a wicked dance — with his mom — that grooved on chords struck by two classics (Oedipus, “Napoleon Dynamite”). Like R2D2, Rowley is the comedy relief who often holds the secret to everything, and more of him is needed.

At school, where Greg is pursuing a blond cutie, Holly, who seems out of his league, the usual dreary slapstick embarrassments ensue as Rodrick does his best to sabotage his brother’s romantic efforts. But in a nicely underplayed scene at a nursing home, where each child is visiting a grandparent, Greg finds that being himself is the best way to get to know Holly. With its fondness for devising ways to force Greg to get caught in his underwear or stuck in a ladies’ room amid a terrifying gaggle of octogenarians, the movie might be unaware that it is carrying a nice little hidden message, but it is, and it works.

As the nerdette mom, Rachael Harris also brings a lot of spirited warmth and completely believable adoration for her feuding sons, whom she tries to bribe into liking each other with “Mombucks.” Harris lightly steals the show at the end, when her all-forgiving mompride has her dancing exceptionally mommishly to Rodrick’s heavy-metal band. The audience rightly prefers her to the musical stylings of the band (“Loded Diper”).

As the dad, though, the rapidly declining asset known as Steve Zahn is lost in flailing gestures and flustered cluelessness. He seems to be completing the final stages of his transition to becoming William H. Macy. It makes me feel very old to say this, but: Zahn was once funny.

kyle.smith@nypost.com