April Fool's Day

April Fool's Day or All Fool's Day occurs annually on April 1. The day is generally observed by playing a practical joke on a "victim" who soon becomes known as an April Fool. This custom is thought to have started in France during the 16th century but the British are credited with bringing it to the United States.
The commonly accepted origin of April Fool's Day involves changes in the calendar. At one time, the New Year celebration began on March 25 and ended on April 1. However, in 1582, King Charles IX adopted the Gregorian calendar and accepted the beginning of the new year as January 1. Those who refused to acknowledge the new date or simply forgot received foolish gifts and invitations to nonexistent parties. The butt of such a prank was known as a "poisson d'avril" or "April fish."

There have been numerous hoaxes on this day and according to this site, The Museum of Hoaxes, the following is the best one:

The Swiss Spaghetti Harvest 1957: The respected BBC news show Panorama announced that thanks to a very mild winter and the virtual elimination of the dreaded spaghetti weevil, Swiss farmers were enjoying a bumper spaghetti crop. It accompanied this announcement with footage of Swiss peasants pulling strands of spaghetti down from trees. Huge numbers of viewers were taken in. Many called the BBC wanting to know how they could grow their own spaghetti tree. To this the BBC diplomatically replied, "place a sprig of spaghetti in a tin of tomato sauce and hope for the best."

I know in Spain we do not celebrate April Fool's Day but Holy Innocents' Day (December 28) but the spirit is the same... So, what are your favourite jokes to play on someone?