April Fool's Day or All Fool's Day is of uncertain origin. We know it as a day for practical joking on April 1st. Two of my Aunts go through the ritual every year without fail. One is the fool-er and the other the fool-ee ... always! The rest of us quit the game years ago and just wait to hear their story.

The holiday is considered to be related to the festival of the vernal equinox, which occurs on March 21. In 16th century France, prior to the adoption of the Gregorian calendar, the New Year was observed on April 1. The celebration began on March 25 and lasted eight days. It was similar to the New Year's celebrations of today, complete with parties and dancing into the late hours of the night. Around 1562, under Charles IX of France, the Gregorian calendar was introduced by Pope Gregory for the Christian world and the New Year fell on January 1st. Most of the world has followed this calendar ever since. 

Due to poor communication, many people did not receive word of this change for years. Others were simply obstinate and refused to acknowledge the change. These people continued to celebrate the New Year on April 1st. The general populace labeled them "April fools". They were sent on fool's errands or were tricked into believing that something false was true.

Thus, the tradition of playing pranks on April 1st. It spread to England and Scotland in the 18th century and eventually to the American colonies of both the English and French. April Fool's Day became an international phenomenon, with different nationalities enacting their own unique brand of humor. 

In Scotland it is actually celebrated for two days. The second day is devoted to pranks involving the posterior region of the body and is called "Tally Day." The origin of the "kick me" sign can be traced back to this. 

So on April 1st, tell someone their shoe is untied, set your roommate's clock back an hour or tell your sister (my aunt again!) that eight or ten family members from out of town will be arriving soon to stay at her house.  It can be a fun day whether you play the joke or fall prey. Just remember that you have Pope Gregory's calendar to thank.