April Fool's Day. 1564 CE origin theory.

King Charles IX moves New Year from late March to January 1st. Calendar reform. Those celebrating spring festivals on the old dates? Mocked as poissons d'avril — April fish. Fools. 🐟🗓️

Meanwhile, the festivals survived:
→ India: Ugadi, Gudi Padwa, Chaitra Navratri (March-April)
→ Rome: Hilaria for Cybele (March 25)
→ Persia: Nowruz (March 21)

The joke outlasted the calendar dispute. The festivals outlasted the joke.