Set in 1988, the story unfolds in a music store featuring Matt Franklin (Topher Grace), his twin sister Wendy (Anna Faris), and his best friend Barry Nathan (Dan Fogler). They are pondering the best time to connect with Matt's ideal girl, Tori Frederking (Teresa Palmer). After graduating from MIT, Matt finds himself working at a Suncoast Video store nestled in a local shopping mall, still grappling with his future path. One fateful day, Tori walks into the store, and when she inquires about his job, Matt fabricates a story, claiming he's employed at Goldman Sachs. This unexpected encounter leads Tori to invite him to a Labor Day weekend gathering hosted by Wendy's boyfriend, Kyle Masterson (Chris Pratt).
That evening, Matt, Barry, and Wendy embark on their journey to the party, but before they arrive, Barry impulsively steals a car from the very dealership that recently fired him for poor sales performance. At the party, Kyle dares the guests to ride the "ball," a bizarre hollow steel sphere designed to roll down the street. There, Matt unexpectedly runs into Carlos (Demetri Martin), a former classmate who is indeed working at Goldman Sachs.
As the night unfolds, Barry succumbs to a reckless decision involving cocaine he found in the stolen vehicle, engaging in a spontaneous dance battle. Amidst the excitement, Kyle makes a surprising proposal to Wendy. Leaving the party with Tori and her friends, Matt is swept away to a business soiree in Beverly Hills. During their drive, Tori confides in Matt that her boss, Peter (Michael Ian Black), hired her purely to see her naked. Subsequently, at the party, she shares her disdain for her job, leading to an intimate moment between the two. However, when Matt reveals the truth about his employment, Tori becomes upset and walks away.
On their way back to the party, Barry encourages Matt to seize the night, leading to another poor choice involving cocaine in the glove compartment. Engrossed in their antics, Matt diverts his attention, resulting in a car crash. When they are stopped by Matt's father, Mr. Franklin (Michael Biehn), he only gives them a warning when they deserved much worse. He advises Matt to pursue a more ambitious career.
Upon returning to Kyle's gathering, Wendy confides her anxiety about receiving her graduate school acceptance letter. After Kyle opens it for her, they face the harsh reality of her rejection. Meanwhile, Matt attempts to apologize to Tori, but she remains closed off to him. With Barry still under the influence, he approaches a goth girl, proclaiming his intent to ride the ball. Despite warnings from Barry, Matt volunteers for the challenge, insisting that he can do it. As he climbs inside the ball, Wendy frantically urges Kyle to prevent him from riding. However, once the ball is released, it careens off course, causing chaos as it collides with several cars and dramatically ends up in a neighbor's pool.
Just as Matt nearly drowns, he manages to escape the aquatic trap. Following this near-disaster, he asks Tori for her home phone number, trying to gauge if he's overstepping. Tori admires his daring spirit and gives him her number. In the midst of these events, Wendy, having seen Matt's reckless stunt, decides to end her relationship with Kyle, leaving him heartbroken. As dawn breaks, a triumphant Matt holds onto Tori's number, while Mr. Franklin stumbles upon Matt's Suncoast Video name tag, a reminder of his son's wild escapades from the previous night.
