On the first of April each year, people all over the country play pranks on each other. Even large companies and news outlets have been known to get in on the fun. Like the time Taco Bell released a press release saying they bought the Liberty Bell and were changing the name to the Liberty Taco Bell. 

But setting aside a holiday just for playing pranks on your friends and customers has always seemed a little weird to me, so I decided to do some digging to find out why we celebrate April Fools’ Day.

Turns out, no one is really sure where the holiday originated. But here are three of the most common hypotheses:

Gregorian Calendar

When Pope Gregory XIII introduced the Gregorian calendar, New Year’s Day moved from April 1 to January 1. However, many people refused to recognize the new calendar with the new date for New Year’s. These people were often mocked and pranked for celebrating New Year’s Day four months too late. However, this doesn’t explain the wide spread acceptance of this holiday.

Arrival of Spring

Many cultures set aside a time to celebrate at the beginning of spring, including the ancient Roman festival Hilaria and the Hindu festival Holi. Some believe that April Fool’s Day is just another instance of celebrating the onset of spring.

May Day and Summer Planting

May 1, otherwise known as May Day, was considered the first day of summer in pre-Christian European pagan cultures. Many farmers used to believe that if you planted your crops before this day that you were a fool and would be subjected to Spring’s often unpredictable weather patterns that were sure to ruin your crops. Some argue that this line of thinking inspired the tom-foolery that we associate with April Fools’ Day. 

While no one is certain where April Fools’ Day originated it is common in many countries outside the U.S. It’s called Hunt-the-Gowk Day in Scotland and Poisson d’Avril in France. It seems like everyone finds the humor in a little light-hearted pranking.