Whistling at night is a major taboo in many East Asian cultures.

The superstition against whistling at night is deeply rooted in the folklore of East Asian nations like Japan, China, and Korea. In Japan, the belief is known as 'yoru ni kuchibue o fuku to hebi ga kuru,' which translates to 'if you whistle at night, a snake will come.' This warning was often used by parents to teach children that unnecessary noise could attract dangerous predators or even 'kitsune' (fox spirits) capable of possession.Historically, whistling was also associated with criminals and underworld figures. In Edo-period Japan (1603–1867), burglars and kidnappers used specific whistling patterns as signals to communicate with accomplices without being detected by guards. By discouraging whistling, communities effectively reduced the chances of accidental signaling or drawing the attention of real-world threats.In Chinese culture, the 'k'ou-shao' (whistling) was sometimes linked to the summoning of wandering spirits or 'gui.' Ancient Taoist practices even included 'xiao,' a form of ritual whistling intended to communicate with the spirit world or influence the weather. Because of these spiritual associations, whistling in a domestic setting at night was seen as an invitation to restless souls.Modern sociologists view these taboos as 'social control mechanisms' designed to maintain peace in densely populated areas. By attaching a supernatural consequence to noise, elders could ensure a quiet environment for the community. Today, while few people literally fear ghosts, the cultural etiquette remains a strong social norm across East Asia.