Loved by pranksters but loathed by teachers and those who are easily spooked, we can all agree that April Fool’s Day is one of the world’s silliest holidays. But did you know that the Catholic Church might have had a hand in cementing it on the calendar? According to this Catholic News Agency article, it was Pope Gregory XIII who unknowingly gave rise to April Fool’s Day by ordering all Christian nations to adopt the Gregorian calendar. Those who didn’t were called fools, and would have paper fish or ‘poisson d’avril’ (April fish) attached to their backs, said to symbolize a young, easily caught fish and a gullible person.
Source: mocatholic.org