Thirteen-year-old Eric Larson is a brainiac willing to do anything to become popular, even telling a lie the size of an elephant-or in his case, a monkey. Determined to reinvent himself and not live in the shadow of his brother, Eric returns to high school after summer vacation tanned, muscular, and confident. But when he spontaneously brags to his classmates that he has a pet monkey, everything changes.

Just as Eric's geek-o-meter levels start to decrease and the super-hot Stacie Hansen begins to notice him, his science teacher volunteers Eric's fictitious pet primate as the latest...