Ned has lost a tooth, and left it under his pillow for the Tooth Fairy. When the fairy comes, though, Newton thinks he's a burglar and attacks him. This results in the Tooth Fairy cursing Ned to have giant teeth, and Ned can only have the curse lifted if he does several tasks for the Fairy, such as counting all the newts in the world and doing his laundry.
Ned's mother is hosting a Snapperware party, and Newton accidentally gets sealed in one of the containers and shipped away. Ned tries to find where the container has gone before it's too late.
Ned has invited two girls, Linda Bliss, and a new girl, to the grand opening of the Friendly Falls Aquarium. Newton notices that Ned is anxious about this, and comes to the conclusion that it's because he's lonely. To help him out, he invites 310 more girls, to keep Ned company.
While on a field trip to the zoo, Ned and Newton decided to go to the bus through the emergency exit in the back. However, they find out that this door is actually a portal to a parallel universe, where the bus is parked in a lot of identical buses. They have to find the right one to get back home.
After a freak accident, Ned and Newton switch bodies. They have to try to act like each other until they can switch back, but this is harder than it sounds.
When Newton overhears Ned rehearsing his lines as a ring bearer at a family member's wedding, he mistakenly thinks Ned is going to marry someone other than Linda. He takes it upon his own to ruin the wedding, not knowing that it's not Ned who's getting married.
While Ned's family is at the beach, a message in a bottle washes ashore, from Ned's long-lost Uncle Sandy. Ned and Newton decide to go rescue him, and get swallowed by a whale, encounter sirens, and get caught in a maelstrom before finding him. It turns out that he helped to invent the microchip, and as such, is a multi-billionaire.
Newton is worried that when Ned grows up, he will get rid of him. When he learns about the story of Peter Pan, however, he decides to take Ned to Neverland, where he won't grow up. Through a comedy of errors, however, Ned and Newton instead uncover an unlicensed video distribution operation.
The carnival is in town, and Ned wants to take Linda to it. He's terrible at most of the carnival games, however, and Rusty McCabe beats him at all of them. Ned finds out later, though, that Rusty's uncle owns the carnival, and has rigged all the games to take the visitors' money and let Rusty win every time.