Young employees at Shenaniganz restaurant band together to fend off the monotony of adulthood through their hilarious shenanigans. The film unfolds during the chaotic first day of a new worker, giving viewers a glimpse into the amusing and often ridiculous ways the waitstaff, including waiters and cooks, pass the time.
Central to the story is Dean (Justin Long), who has been waiting tables for four years post-high school without a degree to show for it. His world is shaken when he finds out from his mother that his former high school friend, Chett (Travis Resor), has achieved a bachelor's degree in electrical engineering. This revelation forces Dean to confront the lack of direction in his life. Meanwhile, Dean's hedonistic friend and colleague, Monty (Ryan Reynolds), mirrors Dean’s uncertainty but has resigned to the idea that his future is anchored in the restaurant itself. Monty is designated to train Mitch (John Francis Daley), a freshly hired waiter who feels continually sidelined throughout the narrative.
Among the eclectic staff, we meet Calvin (Robert Patrick Benedict), a hopeless romantic struggling with his love life, and Dan (David Koechner), the no-nonsense manager who sees potential in Dean and hopes to mentor him. The team also includes a vivacious 17-year-old hostess, Natasha (Vanessa Lengies), the feisty waitress Naomi (Alanna Ubach), the witty waitress Serena (Anna Faris), Dean's supportive girlfriend and fellow waitress Amy (Kaitlin Doubleday), as well as carefree busboys T-Dog and Nick (Max Kasch and Andy Milonakis). The line-up is rounded off by Raddamus (Luis Guzman), the head chef, the chaotic Floyd (Dane Cook), the ever-cool bartender Tyla (Emmanuelle Chriqui), and the reflective dishwasher Bishop (Chi McBride).
As the waitstaff entertain themselves with endless gossip, grievances about customers, and clever pranks, they engage in a peculiar pastime dubbed the "Penis Showing Game." Each character has their own unique issues and stories, which weave intricately with the restaurant's daily hustle and bustle.
Just before closing time, Chett arrives with his girlfriend and, out of pity, leaves a significant tip for Dean. This unexpected gesture spurs Dean to make a bold choice: he resigns from his job, rejecting the assistant manager role offered by Dan at the film’s beginning, and embarks on a quest for a more promising future.
The evening culminates in a wild party at Monty and Dean's house. At the gathering, Monty manages to fend off advances from Natasha (promising to hook up once she turns 18), Calvin tries to address his romantic dilemmas, and Mitch lashes out at the team, finally branding them with a comical keepsake from the "Penis Showing Game." Monty, impressed, reveres Mitch as a deity. The film wraps up with the staff reminiscing about the day's absurdities, Dan arriving at the wrong address for a disgruntled customer, and the debut of a music video featuring Nick and T-Dog, capturing the youthful spirit of their shared experiences.
