The minute you wake up on April 1, there's only one thing you need to remember: Trust no one! April Fools' Day has been, well, fooling people for hundreds, and possibly thousands, of years. The exact beginning of the silly holiday is a bit hazy, but its modern history is extremely colorful. Here's a brief overview of every prankster's favorite holiday.

Ancient Roman Hilaria

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The origin of April Fools' Day is a bit of a mystery, but there are several theories. Some historians believe that April Fools' Day, like many modern holidays, may have its roots in ancient Rome. According to the Library of Congress, the Romans used to celebrate a holiday called Hilaria around the vernal equinox, which typically occurs at the end of March. During Hilaria, people participated in all kinds of games, processions, and masquerades. One of the most popular activities was for commoners to dress up as nobility and use their status to "prank" others.

Whether Hilaria is the true basis for our modern April Fools' Day is up for debate, though. Other historians link it to the ancient Romans' Saturnalia festival or the medieval Feast of Fools celebration in France and England.

Modern April Fools' Day

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One of the most commonly cited theories around April Fools' Day involves France's transition from the Julian calendar to the Gregorian calendar, which moved the start of the new year from the vernal equinox to January 1. People who were not up to speed on the change celebrated the new year late and were ridiculed for it. One of the most popular pranks, according to History.com, was to put a paper fish — called a "poisson d'avril," or April fish — on the backs of the delayed revelers. The fish was meant to mark an easy-to-catch or gullible person, otherwise known as an "April fool."

It's a popular (and plausible) theory, but there are other, even earlier references to the holiday elsewhere. In 1561, a Flemish writer published a comical poem about a nobleman who sent his servant to do a series of ridiculous errands on April 1. In the poem, the servant appears to recognize that he might be the butt of an April 1 joke, repeatedly stating that he hopes the nobleman isn't sending him on a "fool's errand."

According to the Library of Congress, John Aubrey also wrote about April Fools' Day in the late 17th century — though not, it should be noted, about how it started. In fact, the question of how April Fools' Day originated was a mystery even back then. As early as 1708, a British magazine asked, "Whence proceeds the custom of making April Fools?" Unfortunately, we may never get a definitive answer.

April Fools' Day around the world

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Many countries celebrate April Fools' Day, but not necessarily in the same way. In France, for example, people still continue the tradition of placing paper fish on their friends' backs. And in most of the U.K. and Ireland, pranks stop at noon. Anyone who tries to play a joke on someone else after that is considered to be a fool themselves. The Greeks, meanwhile, believe that a person who pulls off a successful prank will have good luck for the rest of the year.

Hall-of-fame April Fools' pranks

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Check out some of the best April Fools' Day pranks ever pulled:

  • Annual washing of the lions (1860): According to the Museum of Hoaxes, this prank recurred for several decades, dating as far back as 1698. People in London would be invited to view what was then advertised as the famous annual washing of the lions ceremony at the Tower of London. At noon on April 1, a large crowd of people — mostly folks from out of town — would gather around the tower waiting for the lions, which of course would never appear. This happened regularly for more than a century, but somehow it continued to fool people. In 1860, pranksters took the ruse a step further and actually printed out and distributed tickets and handbills. Hundreds gathered around the Tower of London to watch the nonexistent washing of the lions ceremony. The joke was so successful that the local newspapers reported on it the next day.
  • The Swiss Spaghetti Harvest (1957): Do you know how spaghetti is made? Apparently, it grows on trees! At least, that's what producers of the British news program "Panorama" wanted people to think. On April Fools' Day in 1957, the show aired a segment about the incredible spaghetti bumper crop that Switzerland was experiencing. They even had footage of families pulling cooked pasta straight off of the trees: "For those who love the dish, there's nothing like real, home-grown pasta."
  • Instant color TV (1962): In Sweden in 1962, Sveriges Television pulled a now-famous prank on its viewers. The station reported that if you put a nylon stocking over your black and white television set, you could see the picture in color! The prank reportedly caused thousands of people to rush around their homes in search of stockings to cover their TV sets.