Ryan (played by Troy Gentile), also known as T-Dog, and Wade (portrayed by Nate Hartley), nicknamed Skeletor, are both gearing up for the challenges of high school life. They find themselves in a tough spot as self-proclaimed nerds: while Wade dreams of becoming a magician, Ryan aspires to be a rapper. Wade lives with his stepfather Jim (Ian Roberts) and stepsiblings, along with his mom Barbara (Beth Littleford), while Ryan is raised by his mother Dolores (Lisa Ann Walter).
On their first day at school, chaos strikes when the pair accidentally shows up sporting identical shirts. Things take a turn for the worse when they witness two bullies, Filkins (Alex Frost) and Ronnie (Josh Peck), brutally targeting a fellow geek named Emmit (David Dorfman) by stuffing him into his locker. Wade bravely steps in to help, but soon they all become prey to relentless bullying where they are subjected to humiliating pranks, including being forced to urinate on each other and having their pants dropped in the hallway, with their lockers filled with inappropriate materials.
The other students are too frightened to help, fearing they might become the next targets. Even the principal turns a blind eye, as Filkins enjoys the unfair advantage of being an emancipated minor, leaving him unaccountable for his actions. The situation escalates when Filkins attempts to run the trio down for reporting him. In desperation, Wade suggests hiring a bodyguard to protect them. They place an ad online, leading to a series of bizarre interviews with various shady individuals until they settle on Drillbit Taylor (played by Owen Wilson), a supposed military veteran who offers his services for a mere $83 a week.
Though Drillbit claims to have served on the protection detail for three Vice Presidents, in truth, he is a homeless man who cleans up at a public beach. His ulterior motive for taking the job is to rob the boys to fund his escape to Canada. Accompanied by his homeless friend Don (Danny McBride), Drillbit initially sees them merely as means to an end, calculating his expenses for fleeing.
However, when Drillbit emphasizes that violence is not the solution to dealing with bullies, he begins teaching the boys defensive techniques. Amid numerous fast-food outings and some improvised life lessons—including the infamous hold-back maneuver—he gradually warms up to the trio. He encourages Ryan and Wade to bond with Filkins and Ronnie in hopes of diffusing tension. In a bold move, Ryan challenges Filkins to a rap battle, inadvertently achieving a humiliating victory over him.
As tensions mount further, the boys decide to sneak Drillbit into school as a substitute teacher, which gives them some degree of protection. During this time, Drillbit crosses paths with Lisa Zachey (Leslie Mann), a teacher, and sparks fly, adding a romantic twist to the story.
However, everything comes crashing down when Ronnie discovers Drillbit's secret as a homeless person, leading to him revealing the truth to Filkins. After a confrontation where emotions run high, the boys decide they can no longer trust Drillbit, especially after discovering that he had been stealing from them and that his real name is Bob, a deserter from the U.S. Army.
In a dramatic climax, the boys confront Filkins at his home, where a party is in full swing. After a series of feuds, with each boy throwing in their all, Drillbit resurfaces to save the day, ultimately taking down Filkins after an intense fight that leads to the arrival of the police. Filkins is arrested, destined for a strict living situation in Hong Kong, eliminating the threat he poses.
With the bullies dealt with, Ronnie’s newfound friendship with the boys offers a glimmer of hope. Drillbit, after serving a short stint in jail for desertion, eventually reunites with both Lisa and the boys, embracing his role within their lives. By the end, he has transformed into a school nurse, humorously asking a kid if he might need a bodyguard for his scraped knee. Through their misadventures, a unique bond forms between Drillbit, Ryan, Wade, and Emmit, showcasing a heartwarming journey from bullying to friendship, all while navigating the unpredictable world of adolescence.
