hit the fan

The origin of the phrase remains uncertain, though it is frequently attributed to an old joke involving a lapse in plumbing and a lack of foresight. In the narrative, a man in a crowded bar, unable to locate a bathroom, makes use of a hole in the floor on the storey above. Upon his return, he finds the room empty save for the bartender, who is cowering behind the bar. When the man inquires as to the whereabouts of the patrons, the bartender asks where the man had been when the excrement hit the fan.

Other possible sources include American or Canadian military slang, or perhaps a more literal reference to the mechanical action of agricultural manure spreaders. The phrase functions as a study in the hazards of centrifugal force, recording the moment a private mess becomes a public inconvenience. The exact date of entry into the lexicon is not fixed, leaving the expression as a somewhat unanchored observation on the physics of disaster.