Last night's installment of Celebrity Rehab delivered perhaps its most poignant moment since decided to convert the Pasadena Recovery Center into a melancholy-tinged version of its Surreal Life house. In a move we'll assume is generally unnecessary inside the walls of a rehabilitation facility, Dr. Drew and his troubled, semi-famous charges staged an intervention on behalf of Joanie Chyna in a desperate attempt to figure out why, exactly, she's on the show; as an avowed non-alcoholic or drug-abuser, Joanie's very presence was so bedeviling to her fellow addicts that such a drastic measure was required to puzzle through the mystery of her casting.