A young couple hanging out on a Bronx rooftop after an evening of clubbing fell six stories to their death early Saturday, cops and friends said. The bodies of the victims - identified by friends as Michael Rodriguez, 21, and Melissa Lopez, 19 - lay intertwined in the backyard of a Parkchester building. "That's my son! That's my son! He's my only son," Jackeline Rodriguez wailed as her son's body was removed. "I can't even think right now. I have no words."