Recent internet jokes aside, ancient Roman spring festival of pranks and jesters called Hilaria, on verbal equinox, and Chaucer also made reference to the pranking of innocents, or fools, on Match 32, being first of April. Chaucer wrote in the late 1300s, before the Gregorian calendar adjustment. On paper. Still completely unconnected with actual life, which rusted around crops and hunting. From the perspective of land- and weather-dependent people, a paper change like that would have seemed very foolish. Although the "learned" men of the cities surely believed that the rubes in rural places that raised their food surely were fools.