J.D. wonders what his baby is thinking when Turk asks him to shoot some hoops. Carla suggests that Turk would be better off spending some quality time with his daughter. Meanwhile, Bob mentions to a board member that he has a birthday coming up. When asked how old he'll be, Bob responds, "58." Later, J.D. and Turk hang out with their babies. Both of them miss doing goofy stuff with each other.
Turk and J.D. get the afternoon off from caring for their babies and decide to do something stupid. Cox then checks on his young patient Josh and then tells his parents that Josh has Leukemia. They tell Cox they don't want to tell him yet. By the nurses' station, Elliot announces that she's planning a party for Bob's birthday and asks for help in finding out Bob's real age.
J.D. and Turk plan to create the world's biggest black doctor and assemble some large novelty props. When J.D. shows Cox his huge clipboard, Cox calls J.D. an overgrown 32-year-old baby. Kelso also gives Turk a similar lecture, which forces J.D. to reconsider this prank. "It's probably time for us to grow up," J.D. tells his best friend. Meanwhile, the Janitor learns that Kelso is turning 65 and Cox tells Josh that he has Leukemia.
Turk insists he's not ready to grow up and tells J.D. that, "I'm bringing you back." The Janitor and Elliot then tell Kelso they know his real age, and Kelso says it's none of their business. However, his age comes out when Elliot's party gets underway.
J.D. and Cox sit down with Carla and Turk to hash out the notion of "growing up" versus changing who you are and to talk about telling Josh about his disease - Carla thinks Cox took his childhood away by telling him. Carla insists it's important for everyone to hang onto the "kid inside." J.D. realizes that Turk is right and gets into the giant black surgeon costume. Things are not as fun in Bob's office where a board member tells him that he will be forced to retire because of his age.