It seems that the day before, a traveler visiting the town had shaken hands with a tea vendor who immediately claimed he felt a shock and sensed that his penis had shrunk. He cried out in alarm, gathering a crowd, and a second man then said it also happened to him.

This is not the setup to a joke; it is a real psychological disorder called koro in which victims (mostly men, but sometimes women) come to believe that their genitals are shrinking or retracting into the body. The concern is not only for their sexuality, but also for their lives, since they believe that the condition may be life threatening if not reversed. In order to prevent further shrinkage, victims have been known to securely tie their penises with string or metal clamps — even sometimes having family members hold it in relays until treatment can be sought, usually from shamen or traditional healers. …

“Penis-shrinking panics are a timely reminder that no one is immune from mass delusions and that the influence of culture and society on individual behavior is far greater than most of us would like to admit. Yet the main reason for the absence of penis-shrinking epidemics in Western societies is their incredible nature … but any delusion is possible if the false belief underlying it is plausible.”