When dreamer Larry Guthrie (Larry the Cable Guy) loses his first love to the town hotshot, he decides to win her back by volunteering to help the local children at her after-school program. But when he accidentally tells the kids that the tooth fairy is make-believe, he is soon transformed into a tutu-clad fairy with a sentence of collecting teeth.—HANIBALL
One of the small-town dreamers, Larry Guthrie, is named the "Metro County Miracle." Larry and his girlfriend Brooke stop by a Camaro convertible raffle en route to a child's birthday celebration. Despite Brooke's objections, Larry enters the raffle and wins the opportunity to receive the car. Larry needs to knock down two bowling pins on either side of the lane three times to win. He manages to knock down the bowling pins with the bowling ball after slipping on nacho cheese sauce on his third attempt, which left both pins in place. Following the breakup of Brooke and Larry, Larry learns that Brooke is engaged to Beauregard "Bo" Billings, the town's hotshot. The fact that Bo Billings is running for town mayor inspires Larry to try to win her back.
Larry volunteers at the neighborhood after-school program that Brooke oversees in an effort to regain Brooke's affection. On his first day of volunteering, he upsets a young boy named Gabe by telling him that the Tooth Fairy is not real, leading him to question the Tooth Fairy's veracity. Nyx, a Tooth Fairy, approaches Larry that evening, dresses him in a pink fairy costume, and informs him that he is a stand-in Tooth Fairy who has ten days to gather ten teeth. In addition to being given fairy dust to aid him, Larry is warned that his greatest memory will be erased if he is unable to gather ten teeth.
After waking up from what he initially believed to be a dream, Larry quickly discovers he was mistaken. He transforms into the Tooth Fairy and goes to get his first tooth the next evening. With some difficulty, he collects it, but he is quite proud of his skills. He transforms into the Tooth Fairy once more the following night. He is starting to help the after-school program raise money for new supplies and is making progress there. Brooke tells him she is pleased with his actions and is beginning to warm up to him. In contrast to Bo, who arrives to remove her from Larry, Larry remembers that Brooke is allergic to strawberries and enjoys orange buttercream, which impresses her when the couple goes to test wedding cakes. Then, hoping to further impress Brooke, he offers to use the money they earned to go out and buy the supplies.
Shortly after gathering the program's supplies, Larry transforms into the Tooth Fairy and is compelled to fulfill his role. Bo takes the supplies while he is gathering a tooth in an attempt to discredit Larry. The following day, Larry must tell Brooke and the children the news after returning from picking up the tooth to discover his car empty.
Having lost what he believed to be his best memory, Larry makes the depressing decision to resign from his position as the Tooth Fairy. His confusion arises when he learns that winning the Metro County Miracle was not his favorite memory. Because he has limited time, he resolves to take back his position as the Tooth Fairy. Following the successful extraction of the remaining teeth and the restoration of the children's faith in the Tooth Fairy, Larry discovers that his favorite memory was actually one he had with Brooke. When Brooke asks Bo for his favorite memory, she is disappointed to learn that it has nothing to do with her and recognizes what a self-centered man he is. Larry chooses to share this with her. She breaks off her engagement to Bo and falls in love with Larry again. At his trailer, Bo confronts Larry, who swears to pay back but ends up colliding with a table and getting doused with amnesia powder as he realizes Brooke loves him. By the time the movie ends, Brooke and Larry are married, sharing a house, and soon to have a child. Since the local tooth fairy is ill, Nyx asks Larry to fill in. Larry agrees and takes off into the night to retrieve the tooth.