After having the greatest time of his life three summers ago, Lenny (Adam Sandler), decides he wants to move his family back to his hometown and have them grow up with his gang of childhood friends and their kids. But between old bullies, new bullies, schizophrenic bus drivers, drunk cops on skis, psycho grade school girlfriends and 400 costumed party crashes he finds out that sometimes crazy follows you.

To ease their roommate through a relationship-induced depression, Christina Walters and Courtney Rockcliffe take her out on the town. During their attempts to find her "Mr. Right Now", Christina meets Peter Donahue. Missing her opportunity with him that night, Christina is talked into pursuing him to his brother's wedding.

A happily domesticated grizzly bear named Boog, has his perfect world turned upside down after he meets Elliot, a scrawny, fast-talking one-horned wild mule deer. They both end up stranded together in the woods during hunting season and it's up to the duo to rally all the other forest animals and turn the tables on the hunters.

Elliott incessantly parades proudly with his antlers, until unwise rock-jumping sees them crushed, and thus his new pride. Bride Giselle thinks Elliott has commitment anxiety when he rushes off to take the lead in the rescue of canine buddy Mr. Weenie, who is kidnapped by a poodle's gang of master-devoted pets determined to reconvert him. The feral gang has great trouble even penetrating the heavily guarded holiday resort where the brainwashing attempt is happening.