Three years following the events of the previous film, Lenny Feder (Adam Sandler) has moved his family back to his hometown in Connecticut, where he shared countless memories with his childhood friends. The film kicks off with a humorous scene at the Feder residence, where Lenny awakens to find a wild deer beside his bed. Startled by his wife Roxanne (Salma Hayek), the deer creates chaos by urinating throughout their home. After managing to shoo the deer outside, Lenny rushes to take his children—Greg, Keithie, and Becky—to their last day of school. During the journey, Roxanne mentions the possibility of having another baby, but Lenny insists their family is already complete, leaving her feeling disappointed.
Across town at the Lamonsoff household, Eric Lamonsoff (Kevin James) and his wife Sally are struggling to align their parenting styles. While Sally encourages unwavering support, Eric leans more towards a practical approach. Meanwhile, at the McKenzie home, Kurt (Chris Rock) surprises his wife Deanne with an anniversary gift, only to discover she has entirely forgotten about the occasion.
In an unexpected twist, Marcus Higgins learns at a train station that he has a seventeen-year-old son named Braden. Marcus is taken aback when he meets Braden, a towering teen covered in tattoos, who immediately expresses his disdain for Marcus. After dropping the kids off, Lenny, Eric, Kurt, and Marcus reminisce about their carefree summers and the bully from their youth, Tommy Cavanaugh. Lenny boasts about his supposed ability to beat Tommy—until they unexpectedly run into each other at Becky's ballet recital, where Lenny's fear is palpable.
Post-recital, the group heads to their childhood swimming hole, only to be confronted by a rowdy group of fraternity boys who force them to jump in the water naked. Braden, witnessing this humiliation, chooses to vandalize their frat house in retaliation. When the fraternity boys discover what happened, they vow revenge.
Back home, Lenny assists Roxanne with preparations for an 1980s-themed party. As festivities begin, Marcus bonds with Braden, realizing he may have misjudged their relationship. Roxanne persists in discussing the possibility of another child, which proves overwhelming for Lenny, especially when she surprises him with the news of her pregnancy. While numb from the revelation, he seeks solace in drinks with his friends.
The party initially flows smoothly until Tommy shows up, disrespecting Lenny publicly. In an unexpected twist, Lenny challenges Tommy to a fight, only for Tommy to back down, agreeing to take a dive for the sake of Lenny's reputation in front of his kids. This leads to a newfound respect between the two. However, the night takes another turn as the fraternity boys show up, seeking payback for their vandalized property. A brawl ensues, with the locals standing their ground until the frat boys flee in defeat.
With the dust settling, the four friends unwind with pancakes at Eric's mother's house, where she reassures Lenny that a new baby truly enriches life. This heartfelt conversation prompts Lenny to reconsider his earlier stance, leading him to apologize to Roxanne and express excitement about welcoming their new addition, ultimately solidifying their bond.
