Historians believe the day started being celebrated after Pope Gregory XIII introduced the Gregorian calendar and ruled that the new calendar starts from January 1 back in 1952, instead of March end when New Year used to be celebrated.
It was April 1, as believed, when the change of calendar from Julian to Gregorian was initiated, hence making it the most commonly believed reason for celebrating the day.
The first country to accept and implement the new calendar was France. But not all countries did the same. Some refused to accept the change and continued following the Julian calendar. Consequently, the ones who did not follow the new calendar started being considered foolish and made fun of by those who did.
The day is looked forward to for all the fun and smile it spreads, the laughter it generates and the guilt-free leg pulling one can do – all in jest and good spirit.