Three childhood friends—Dean, [Wes](gaius-nolan), and JT—pull a classic prank on Halloween night in 1999 by setting fire to a bag of dog feces left on the doorstep of their neighbor. This act inadvertently ignites a scarecrow, and in a twist of fate, Dean scribbles the name "Ricky Stanicky" on a costume piece, which leads the authorities to believe an out-of-town boy is behind the incident. Two decades later, the trio continues to use the fictitious Ricky Stanicky as an excuse to dodge responsibilities and avoid the repercussions of their actions.
As life unfolds, JT and his wife, Susan, are gearing up for a baby shower, supported by Dean and his girlfriend, Erin. Amid the preparations, Dean receives a distressing call from "Ricky," who is, in fact, Wes impersonating him. Wes claims to be alone and battling a recurrence of testicular cancer in Albany, prompting Erin and Susan to encourage Dean and JT to visit him.
However, the truth is that the friends have secured tickets to a Marc Rebillet show in Atlantic City, New Jersey. On the flight, they turn off their phones, impersonate Ricky yet again, and meticulously document their lies about Ricky in a makeshift Bible. Their adventure takes a comedic turn when they encounter Rock-Hard Rod (played by John Cena), an over-the-top impersonator whose antics quickly wear thin on the group.
When Dean learns that Susan has gone into labor unexpectedly, they rush back to the hospital, where the trio discover that she has given birth to a son named Whitaker. The situation becomes more complicated as JT's skeptical mother-in-law, Leona, questions the existence of Ricky Stanicky. In an attempt to save face, Wes nearly reveals the truth, but Dean cleverly twists the narrative to suggest Ricky is celebrating five years cancer-free alongside his friends, leading to invitations for Ricky to attend the baby’s Bris.
Wes, seeking a reprieve from his partner, uses Ricky as a cover-up, but soon Dean decides to hire Rod to embody Ricky Stanicky. They share their fabricated "Ricky Bible" with Rod, informing him about their intricate web of lies. At the Bris, Rod charms everyone with his larger-than-life persona, winning over Leona and even impressing Ted Summerhayes—Dean and JT's boss—with his knowledge about an imminent corporate merger.
In a series of hilarious misadventures, Rod finds himself unwittingly involved in various antics, including an accidental mishap during the circumcision of Whitaker due to an unexpected Ketamine incident. Ultimately, the fantasy spirals when Ted hires Rod to oversee the merger deal with World River, which enrages Dean and JT who feel overshadowed by their own creation.
Meanwhile, Erin, keen on pursuing a story about Ricky's "heroic" deeds, reveals to Dean that she knows the truth about Rod's identity. This revelation sends Dean into a spiral as he grapples with losing both his job and Erin. The tension culminates at a company party where Dean chooses to confess the reality behind Ricky Stanicky, prompting a series of reactions from the attendees that leads to a pivotal merger decision.
As the story unfolds, Dean faces the consequences of their deception while realizing the importance of true relationships and honesty. The narrative wraps up with a heartwarming montage showing the characters' growth and changes, depicting moments such as Carly planning her engagement with Rod and everyone coming together to address environmental issues, highlighting a newfound purpose forged through their chaotic journey.
