S6, E18: Three's a Crowd - Keri Russell Guest Stars - J.D. (Zach Braff) feels a little left out when Eliot's (Sarah Chalke) wild sorority sister, Melody (Keri Russell) comes to town. Not able to deal with being the third wheel he turns the girls against each other in the hopes that he will once again be Eliot's priority friend and, if he is lucky, that he might get to "mash" it with Melody. Meanwhile, Turk (Donald Faison) and Dr. Cox (John C. McGinley) go head to head when they disagree over whether or not a patient requested surgery is necessary. Elsewhere, Carla (Judy Reyes) discovers an unlikely ghost haunting pediatrics in an attempt to keep it clean. In the end one of Sacred Hearts own will be considering a marriage proposal. Ken Jenkins and Neil Flynn also star.