Eighty-six-year-old Irving Zisman embarks on a cross-country trip to take his eight-year-old grandson, Billy, to live with his father after Billy's mother is sent to prison. Along the way, Irving tries to expose Billy to life's harsh realities through a series of wildly inappropriate and outrageous practical jokes. Their adventure leads them into encounters with unsuspecting strangers in a variety of settings, including diners, wedding stores, and beauty pageants. Each interaction provides comedic fodder as Irving's crude behavior and sharp tongue catch everyone off guard.

As they journey onwards, the bond between Irving and Billy grows stronger despite the chaos surrounding them. Irving's shenanigans draw varied reactions of shock, laughter, and disbelief from innocent bystanders who are unaware they are part of an elaborate prank. Alongside the humor, a touching narrative emerges as both characters reveal their vulnerabilities, underlying the importance of family and connection amidst the ridiculous antics.