The last stall on the left is oversized, big enough for two people. Y.T.'s mom goes in, followed by the proctor, who closes and locks the door. Y.T.'s mom pulls down her panty hose, pulls up her skirt, squats over a pan, pees. The proctor watches every drop go into the pan, picks it up, empties it into a test tube that is already labeled with her name and today's date.