Is your cell phone call really that important that you have to keep the convo going while you're doing your business in a bathroom stall? Really? Do you tell the person on the line that the sound of running water is a faucet and not your bladder? And have some respect for your fellow pee-ple—we might be trying to have a moment of peace away from the maddening crowd (or perhaps we're communing with our US Weekly).
Pry the phone away from your ear, urinate, wash your hands, punch yourself in the face, and resume your call.