Popularly known as bashful bladder, shy bladder, stage fright, pee shy, etc. A social phobia with both physical and psychological aspects that make it impossible to urinate when anyone else is near by.
One guy to another: "My bladder is bursting and I can't pee a drop with all these guys lined up behind needing to piss at this urinal." The other guy: "I can't go if anyone is standing next to me." Meanwhile in the ladies' room: "I wish those girls trying to get into this stall would just shut up so I can relax and get all this pee out that I have been holding for 6 hours."