April 1 has become synonymous with outrageous and ludicrous claims, announcements for things that never come to be, and things that are downright impossible. April 1 is a day to fool.

How did this tradition ever come to be? Nobody knows. There are a number of origin theories, some as far back as the 1500s, from a whole range of countries. In particular, British folklore points to the village of Gotham in Nottinghamshire to the origin of the foolish holiday.

In the 13th century, it was traditional for any road the King placed his foot upon to become public property. According to legend, when the people of Gotham heard King John was traveling and would be coming through their village, they refused him entry, as they didn’t want to lose their main road.

Furious, the king sent his soldiers into the town, but they found a town full of lunatics conducting foolish activity including drowning fish and caging birds in roofless fences. While it was an act, the King fell for it. He declared the town too foolish to warrant punishment.

Ever since then, so the legend goes, April Fools’ Day honors their trickery.

Today, people expect everybody to do something foolish, so sometimes the best “pranks” are the ones that happen to be true. Gmail, for example was announced on April 1, 2004. Also, due to a bad case of language barrier, on April 1, 2014, North Korea named its “civilian” space program the National Aerospace Development Administration, otherwise known as NADA.