April Fools' DayApril Fools' Day (alternatively April Fool's Day, sometimes All Fools' Day) is celebrated on April 1 every year. April 1 is not a national holiday, but is widely recognized and celebrated in various countries as a day when people play practical jokes and hoaxes on each other called April fools.In Italy, France and Belgium, children and adults traditionally tack paper fishes on each other's back as a trick and shout "April fish!" in their local languages (pesce d'aprile!, poisson d'avril! and aprilvis! in Italian, French and Flemish, respectively). Such fish feature prominently on many late 19th to early 20th century French April Fools' Day postcards.The earliest recorded association between April 1 and foolishness is an ambiguous reference in Chaucer's Canterbury Tales (1392). Many writers suggest that the restoration of January 1 by Pope Gregory XIII as New Year's Day of the Gregorian Calendar in the 16th century was responsible for the creation of the holiday, sometimes questioned for earlier references.Precursors of April Fools' Day include the Roman festival of Hilaria, held March 25, and the Medieval Feast of Fools, held December 28, still a day on which pranks are played in Spanish-speaking countries.In Chaucer's Canterbury Tales (1392), the "Nun's Priest's Tale" is set Syn March bigan thritty dayes and two. Modern scholars believe that there is a copying error in the extant manuscripts and that Chaucer actually wrote, Syn March was gone. Thus, the passage originally meant 32 days after April, i.e. May 2, the anniversary of the engagement of King Richard II of England to Anne of Bohemia, which took place in 1381. Readers apparently misunderstood this line to mean "March 32", i.e. April 1. In Chaucer's tale, the vain cock Chauntecleer is tricked by a fox.In 1508, French poet Eloy d'Amerval referred to a poisson d’avril (April fool, literally "April fish"), a possible reference to the holiday. In 1539, Flemish poet Eduard de Dene wrote of a nobleman who sent his servants on foolish errands on April 1. In 1686, John Aubrey referred to the holiday as "Fooles holy day", the first British reference. On April 1, 1698, several people were tricked into going to the Tower of London to "see the Lions washed".In the Middle Ages, up until the late 18th century, New Year's Day was celebrated on March 25 (Feast of the Annunciation) in most European towns. In some areas of France, New Year's was a week-long holiday ending on April 1. Many writers suggest that April Fools originated because those who celebrated on January 1 made fun of those who celebrated on other dates. The use of January 1 as New Year's Day was common in France by the mid-16th century, and this date was adopted officially in 1564 by the Edict of Roussillon.Longstanding customsIn the UK, an April fool joke is revealed by shouting "April fool!" at the victim, who becomes the "April fool". A study in the 1950s, by folklorists Iona and Peter Opie, found that in the UK, and in countries whose traditions derived from the UK, the joking ceased at midday. A person playing a joke after midday is the "April fool" themselves. But this practice appears to have lapsedin more recent years.In Scotland, April Fools' Day is traditionally called Hunt-the-Gowk Day ("gowk" is Scots for a cuckoo or a foolish person), although this name has fallen into disuse. The traditional prank is to ask someone to deliver a sealed message requesting help of some sort. In fact, the message reads "Dinna laugh, dinna smile. Hunt the gowk another mile". The recipient, upon reading it, will explain he can only help if he first contacts another person, and sends the victim to this person with an identical message, with the same result.In Iran, jokes are played on the 13th day of the Persian new year (Nowruz), which falls on April 1 or April 2. This day, celebrated as far back as 536 BC, is called Sizdah Bedar and is the oldest prank-tradition in the world still alive today; this fact has led many to believe that April Fools' Day has its origins in this tradition.The April 1 tradition in France, Romandy and French-speaking Canada includes poisson d'avril (literally "April's fish"), attempting to attach a paper fish to the victim's back without being noticed. This is also widespread in other nations, such as Italy, where the term Pesce d'aprile (literally "April's fish") is also used to refer to any jokes done during the day. This custom also exists in certain areas of Belgium, including the province of Antwerp. The Flemish tradition is for children to lock out their parents or teachers, only letting them in if they promise to bring treats the same evening or the next day.In Poland, prima aprilis ("April 1" in Latin) is a day full of jokes; various hoaxes are prepared by people, media (which sometimes cooperate to make the "information" more credible) and even public institutions. Serious activities are usually avoided. This conviction is so strong that the anti-Turkish alliance with Leopold I signed on April 1, 1683, was backdated to March 31.Other prank days in the worldIn Denmark, May 1 is known as "Maj-kat", meaning "May-cat", and is also a joking day. May 1 is also celebrated in Sweden as an alternative joking day. When someone has been fooled in Sweden, to disclose that it was a joke, the fooler says the rhyme "april april din dumma sill, jag kan lura dig vart jag vill" (April, April, you stupid herring, I can fool you to wherever I want") for April 1 jokes, or "maj maj måne, jag kan lura dig till Skåne" (May May moon, I can fool you into Scania) for May 1 jokes. Both Danes and Swedes also celebrate April Fools' Day ("aprilsnar" in Danish). Pranks on May 1, are much less frequent. Most Swedish and Danish news media outlets will publish exactly one false story on April 1, for newspapers this will typically be a first-page article but not the top headline.December 28 is the equivalent day in Spain and Ibero-America, which is also the Christian day of celebration of the "Day of the Holy Innocents". The Christian celebration is a holiday in its own right, a religious one, but the tradition of pranks is not, though the latter is observed yearly. After somebody plays a joke or a prank on somebody else, the joker usually cries out, in some regions of Ibero-America: "Inocente palomita que te dejaste engañar" ("You innocent little dove that let yourself be fooled"). In Mexico, the phrase is "Inocente Para Siempre!" which means "Innocent Forever!". In Argentina, the prankster says "Que la inocencia te valga!" (which roughly translates as a piece of advice on not to be as gullible as the pranked) In Spain, it is common to say just "Inocente!" (which in Spanish can mean "Innocent!", but also "Gullible!"). Nevertheless, on the Spanish island of Minorca, "Dia d'enganyar" ("Fooling day") is celebrated on April 1 becauseMenorca was a British possession during part of the 18th century.Television stationsSpaghetti trees: The BBC television programme Panorama ran a hoax in 1957, showing Swiss harvesting spaghetti from trees. They had claimed that the despised pest, the spaghetti weevil, had been eradicated. A large number of people contacted the BBC wanting to know how to cultivate their own spaghetti trees. It was, in fact, filmed in St Albans.Decades later CNN called this broadcast "the biggest hoax that any reputable news establishment ever pulled".Smell-o-vision: In 1965, the BBC purported to conduct a trial of a new technology allowing the transmission of odor over the airwaves to all viewers. Many viewers reportedly contacted the BBC to report the trial's success.In 2007, the BBC website repeated an online version of the hoax.In 2008, the BBC reported on a newly discovered colony of flying penguins. An elaborate video segment was even produced, featuring Terry Jones walking with the penguins in Antarctica, and following their flight to the Amazon rainforest.Radio stationsJovian-Plutonian gravitational effect: In 1976, British astronomer Sir Patrick Moore told listeners of BBC Radio 2 that unique alignment of two planets would result in an upward gravitational pull making people lighter at precisely 9:47 am that day. He invited his audience to jump in the air and experience "a strange floating sensation". Dozens of listeners phoned in to say the experiment had worked.Death of a mayor: In 1998, local WAAF shock jocks Opie and Anthony were discussing April Fool's Day hoaxes, and sardonically stated that Boston mayor Thomas Menino had been killed in a car accident. Menino happened to be on a flight at the time, lending credence to the prank as he could not be reached. The pair repeated that the mayor was dead several times throughout the broadcast, however listeners who tuned in late to the broadcast did not hear that they were repeating a bit, and when they pretended to tell the "news" to an unsuspecting listener (the listener thought she was calling a different show), the rumor spread quickly across the city, eventually causing news stations to issue alerts denying the hoax. The pair were fired shortly thereafter. Archers theme tune change: BBC Radio 4 (2005): The Today Programme announced in the news that the long-running serial The Archers had changed their theme tune to an upbeat disco style.iBod: Every year, National Public Radio in the United States does an extensive news story on April 1. These usually start off more or less reasonably, and get more and more unusual. A recent example is the story on the "iBod," a portable body control device.In 2008 it reported that the IRS, to assure rebate checks were actually spent, was shipping consumer products instead of checks. It also runs false sponsor mentions, such as "Support for NPR comes from the Soylent Corporation, manufacturing protein-rich food products in a variety of colors. Soylent Green is People". Canadian three-dollar coin: In 2008, the CBC Radio program As It Happens interviewed a Royal Canadian Mint spokesman who broke "news" of plans to replace the Canadian five-dollar bill with a three-dollar coin. The coin was dubbed a "threenie", in line with the nicknames of the country's one-dollar coin ("loonie" due to its depiction of a common loon on the reverse) and two-dollar coin ("toonie").Country to metal: Country and gospel WIXE in Monroe, North Carolina does a prank everyyear. In 2009, midday host Bob Rogers announced he was changing his show to heavy metal. This resulted in numerous phone calls, but about half were from listeners wanting to request a song. Hoax phone call to Mandela: In 1998, UK presenter Nic Tuff of West Midlands radio station pretended to be the British Prime Minister Tony Blair when he called the then South African President Nelson Mandela for a chat. It was only at the end of the call when Nic asked Nelson what he was doing for April Fools' Day that the line went dead.U2 live on rooftop in Cork: In 2009, hundreds of U2 fans were duped in an elaborate prank when they rushed to a shopping centre in Cork believing that the band were playing a surprise rooftop concert. The prank was organised by Cork radio station RedFM. The band were a tribute band called U2opia.在欧美一些国家，阳历4月1日是愚人节（幽默节），这一天，人们以多种方式开周围的人的玩笑，上当者当被告知是愚人节时，才恍然大悟，所以这一天总是能够引出许多笑话，不过某些玩笑也会因开得过大而引起人们的恐慌，或改变形势衍生成为（网络）谣言与都会传奇。
