Happy All Fool's Day
April Fools' Day.
Also called All Fools' Day
Type Cultural, Western
Significance Practical pranks
Date April 1
Observances Humour
April Fools' Day is celebrated in many countries on April 1 every year. Sometimes referred to as All Fools' Day, April 1 is not a national holiday, but is widely recognized and celebrated as a day when people play practical jokes and hoaxes on each other.
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 French late 19th to early 20th century 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.[1]
Precursors of April Fools' Day include the Roman festival of Hilaria, held March 25,[2] and the Medieval Feast of Fools, held December 28,[3] 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.[4] Modern scholars believe that there is a copying error in the extant manuscripts and that Chaucer actually wrote, Syn March was gon.[5] Thus, the passage originally meant 32 days after April, i.e. May 2,[6] 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.[7] In Chaucer's tale, the vain cock Chauntecleer is tricked by a fox.
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http://en.wikipedia.org/wiki/April_Fools%27_Day