April Fools’ pranks are an old tradition in American and European cultures, but no one knows the exact origins of the holiday.
One of the most popular theories has to do with changing calendars in the 1500s. According to this explanation, the new year had been traditionally celebrated at the start of spring. When France changed to the Roman calendar, the new year fell in January. Those who were slow to adopt the change, often people who lived in the countryside, became known as "April fools," according to the story.
Other historians have linked the trickster tradition to ancient European spring festivals where people dressed in costume to fool each other. As the holiday spread throughout Europe and to the Americas, pranks became a rite of spring. As the years passed, the pranks got bigger and bigger. Here are a just a few of the greatest April Fools hoaxes in history.