Sonny Koufax, a 32-year-old law school graduate living in New York City, has made a career out of avoiding responsibility. With a job as a toll booth collector and living off a settlement from a minor accident, he watches his friends grow up and move forward while he remains contentedly stuck in perpetual adolescence. His girlfriend, fed up with his lack of ambition, is on the verge of leaving him.

Everything changes when a five-year-old boy named Julian suddenly appears at his door. The child, as Sonny discovers, is the biological son of his roommate Kevin, who’s away on a business trip in China. Through a series of misunderstandings and Sonny’s impulsive decision, he decides to take care of Julian, seeing it as an opportunity to prove to everyone – especially his girlfriend – that he can be responsible.

What begins as a scheme to impress others transforms into a genuine journey of growth and love. Sonny’s unorthodox parenting methods – like letting Julian name himself “Frankenstein” and wear whatever he wants – raise eyebrows, but they also reveal a natural talent for connecting with children. Through daily adventures around New York City, from Central Park to local diners, Sonny and Julian form an inseparable bond.

The story takes a touching turn as Sonny fights to maintain custody of Julian when social services discovers the truth. His transformation from a carefree slacker to a devoted father figure becomes the heart of the narrative. With the help of Layla (Joey Lauren Adams), a lawyer who sees the genuine love between Sonny and Julian, he battles in court to keep the child who has changed his life.

Adam Sandler brings both his signature humor and surprising emotional depth to Sonny, creating a character who grows from a man-child into a responsible adult through the power of unexpected fatherhood. The film balances laugh-out-loud moments with tender scenes that showcase the beautiful evolution of their relationship.

“Big Daddy” becomes more than just a comedy – it’s a heartwarming tale about how love and responsibility can come from the most unexpected places, and how sometimes the best families are the ones we choose for ourselves.