J.D. (Zach Braff) decides that it's time to stop acting like a baby so he can take care of one, but when he stops participating in pranks Turk (Donald Faison) starts a mission to bring his buddy back to immaturity. While, J.D. tries to play the adult Dr. Cox, much to Carla's (Judy Reyes) protest, feels the need to deliver sobering news -- which causes a young patient to grow up too fast. Elsewhere, Eliot (Sarah Chalke) is on a mission to throw Kelso (Ken Jenkins) a birthday party, but little does she know that revealing his true age will set in motion some big changes for Sacred Heart.

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