After completing an arduous seven years at college, Thomas R. "Tommy" Callahan III (Chris Farley) barely manages to graduate from Marquette University and makes his way back to his hometown of Sandusky, Ohio. There, he is welcomed by his father, the prominent industrialist and widower Thomas R. "Big Tom" Callahan, Jr. (Brian Dennehy), who gifts him an executive position at the family's auto parts company, Callahan Auto. In addition to offering Tommy a place in the family business, Big Tom surprises him with news of his engagement to Beverly Barrish-Burns (Bo Derek), a woman he met during a stay at a fat farm. This new development also means that Beverly's son Paul (Rob Lowe) will become Tommy's stepbrother.
However, at the wedding ceremony, tragedy strikes as Big Tom unexpectedly suffers a heart attack and passes away. After the funeral, a gloomy atmosphere descends over the company; the bank, shaken by the loss, retracts its promise of a loan for a new brake pad division and demands immediate repayment of Callahan Auto's debts. Ray Zalinsky (Dan Aykroyd), the owner of a rival company—Zalinsky Auto Parts—steps in with an offer to buy out Callahan Auto while the company's shares are still desirable. Nevertheless, Tommy proposes an alternative: to secure the bank's support with a deal that allows it to retain his inherited shares and house in return for helping the brake pads sales. The bank consents, but with a catch—they require proof of the company's viability by selling 500,000 brake pads. Failure means bankruptcy, while success opens avenues for Big Tom's brake pad venture.
Determined, Tommy embarks on a cross-country sales journey alongside his father's overly devoted assistant, Richard Hayden (David Spade), leading to a comedic exploration of their initially fraught relationship, fraught with tension. On their way, they face numerous obstacles, including car troubles and Tommy's social anxiety impacting sales prospects. Yet, amidst this chaos, Tommy's unique talent for reading people begins to shine through, allowing him to connect and ultimately sell effectively as they reach their sales target.
Unbeknownst to them, Beverly and Paul are revealed to be scheming con artists rather than a mother and son duo. As Paul sabotages company computers to dim their sales achievements, Beverly quickly approves the sale of Callahan Auto to Zalinsky, believing it to be their best escape plan. Tommy and Richard, determined not to give in, manage to travel to Chicago disguised as flight attendants to confront Zalinsky. However, their desperation leads them to devise a bold plan: using road flares, they attract the attention of live television news, and with Michelle—a sales manager who teams up with them—they crash a crucial meeting.
Through sheer resilience and clever persuasion, Tommy invokes Zalinsky's own catchphrase, emphasizing support for "the American working man." This strategy captivates television viewers back in Sandusky and prompts Zalinsky to consider their demands. Unbeknownst to them, Michelle reveals Beverly's hidden criminal past; her marriage to Big Tom was illegitimate, creating substantial stakes. As the truth unfolds, the tables turn—Tommy, now recognized as Big Tom's rightful heir, secures the company from Zalinsky's grips, rendering their deal null and void.
In the film's climactic finale, Tommy rises to lead Callahan Auto Parts, delivering a heartfelt speech to his dedicated employees, ensuring they feel valued. As the story draws to a close, it captures a poignant moment with Tommy reflecting on his father's legacy while drifting on a serene lake, ready to embark on new adventures with Michelle's family.
