April Fools' Day
The term "All Fools," was probably meant as a deliberate stab at All Saints (November 1) and All Souls (November 2) Day. Although the origin of playing practical jokes and pranks on this day is hazy, many folklorists believe it may go back to 16th-century France. At that time, New Year's Day was March 25, with a full week of partying and exchanging gifts until April 1. In 1582, the Gregorian calendar moved New Year's Day to January 1. Those who forgot or refused to honor the new calendar were the butts of jokes and ridicule. Weather folklore states, "If it thunders on All Fools Day, it brings good crops of corn and hay."