April Fools' Day

April Fools' Day is a holiday celebrated on 1 April in both the Muggle and wizarding world. It is celebrated by playing jokes and pranks on others.

Known April Fools' Day pranks

 * 1937: Caractacus Phelps dropped over eight-hundred Stink Pellets off the roof of the Daily Prophet office in Diagon Alley, causing aproxmiately five-hundred cases of Stinkitus.
 * Before 1994: A witch sneaks up behind Alastor Moody and says "Boo!", causing an over-reaction on his part.

Behind the scenes

 * Fred and George Weasley were born on 1 April, most likely as a reference to this holiday, as the twins are notorious pranksters.
 * The video game review site IGN is well-known for making hoax videos on April Fools' Day. In 2011, their hoax was Harry Potter themed: a fake television spin-off called The Aurors.