On December 20, best friends Tommy and Fred skip their final day of school before the winter break. Both are ardent fans of Green Day and aspire to become successful musicians with their band, the Analog Dogs. Tommy shares a home with his older brother Wayne and their mother, while their cautious and reserved drummer, Chad, often acts as the voice of reason.
After the two boys fail to sneak into a Green Day concert in their hometown, they embark on a quest to experience the band live. As Christmas approaches, Tommy receives his father's vintage jacket and a 4-track recorder from his mother, which fuels his passion for music further.
The adventure takes a comedic turn when Wayne's best friend, Keith, pulls a prank on Tommy and Fred, convincing them that the Analog Dogs have been chosen to open for Green Day during a New Year's Eve concert in Los Angeles. Believing this to be true, the boys impulsively decide to journey to Los Angeles, borrowing Wayne's car without permission, despite Tommy lacking a driver's license. Initially hesitant, Chad steps back upon realizing that the promised opportunity might just be a joke.
Their road trip quickly descends into chaos. Disaster strikes as Tommy loses his phone, and they inadvertently fill Wayne's vehicle with diesel fuel, leaving them stranded. In a stroke of luck, they discover Chad's emergency credit card, enabling them to fund their escapade. They even enter a small local music competition, where they perform as the Analog Dogs. Although they win, they are disqualified upon revealing their status as high school students.
Struggling to repair Wayne's car, the trio resorts to commandeering an ice cream truck to continue towards Los Angeles. During their travels, they meet Olivia and her sister while they are on the hunt for ice cream. Their day leads them to a venue called the Hole, where the Analog Dogs perform “Freaking Out.” Meanwhile, Fred, having consumed mushrooms that Keith had hidden in Wayne's car, experiences a series of surreal hallucinations.
As the journey unfolds, Chad becomes increasingly frustrated with Tommy and Fred's antics and questions his role in the band. He feels alienated from their punk rock spirit and decides to leave the Analog Dogs. However, the friendship between Tommy and Fred deepens as they argue but also realize their reliance on each other. Chad ultimately decides to reunite with them. Although his mother initially denies him help to get to Los Angeles, he changes his mind after recognizing the significance of the trip to his friends. Thus, he drives his mother’s van toward the much-anticipated city.
Upon reaching the Green Day concert, the trio takes on the challenge of sneaking inside. Chad disguises himself as the venue's mascot while Fred uses VIP passes to gain access. Unfortunately, Tommy is caught by security, but the friends persevere and get close to the stage. Wayne eventually locates Tommy and admits that the invitation to open for Green Day was merely a prank. Despite this revelation, the boys opt to stay and enjoy the concert. As fate would have it, Fred is unexpectedly invited to join the band onstage to play guitar, an experience that motivates the Analog Dogs to pursue their music with renewed passion.
Following the concert, Tommy, Fred, and Chad discover that Green Day has listened to the Analog Dogs’ song "Bored" and appreciated it. In a surprising turn of events, Green Day extends an invitation for the young band to perform and record their music, presenting the Analog Dogs with a golden opportunity to chase their dreams of becoming a real punk-rock band.
As the friends journey home, Wayne drives the minivan back to the Hole where Tommy has a heartfelt reunion with Olivia, who joins them along with Wayne's mother, creating a sweet concluding moment to their adventurous escapade.
