<P> In the film's opening in the Feder household, Lenny wakes up to find a wild deer standing next to his bed . Lenny tries to get his wife Roxanne to open the window . She wakes up in anger and startles the deer, causing it to urinate all over the bed and on Lenny . The deer runs down the hall and crashes into the bathroom where it runs into Lenny's elder son Greg showering, scaring him and making the deer urinate on him . It turns out that Lenny's daughter, Becky, left the door open overnight for any animals that wanted to come in . Lenny is able to get the deer out of the house by using Becky's monkey doll, which rips it apart, devastating her . Greg, Keith, and Becky then go to their last day of school . Roxanne brings up the idea of their family having another baby, but Lenny says their family is perfect as is, upsetting Roxanne . </P> <P> At the Lamonsoff household, Eric Lamonsoff and his wife Sally are at odds with each other over how to raise their children - Sally believes in unwavering support while Eric prefers to be more practical with them, as proven for their son's bad math skills and daughter's rambunctious sense in fashion . At the McKenzie household, Kurt surprises his wife Deanne with a thoughtful anniversary present, only to find that she has completely forgotten . Meanwhile, Marcus Higgins is waiting at a train station after receiving a letter from an old girlfriend, who tells him that he has a seventeen - year - old son Braden . Marcus is stunned to see a tattooed, six - foot - tall boy, who turns out to be Braden . Marcus tries to be nice and takes him to school, but Braden shows an immediate dislike toward him, believing that he abandoned him and his mother . </P> <P> After dropping off their kids, Lenny, Eric, Kurt, and Marcus form as a group and spend the day roaming around town, reminiscing about the amazing summers they used to have when they were little and Lenny's bully, Tommy Cavanaugh . Lenny argues that he could take Tommy as a little boy and he can still take him . Eventually, the friends go to see Becky's ballet recital, where Lenny runs into Tommy, whom Lenny is visibly terrified of . Tommy threatens that if Lenny ever lies again about being able to beat him up, he'll publicly beat Lenny up . </P> <P> Once the kids are out of school, Lenny, Eric, Kurt, and Marcus decide to visit the old quarry, where they used to swim as little boys . However, they encounter a gang of partying college frat boys who force them to jump into the quarry lake naked . Braden, who was partying with the frat boys, witnesses this and goes off to vandalize their frat house . When the frat men return, they swear to take revenge . </P>

Who plays the little boy in grown ups