In Scotland April Fools' Day is actually celebrated for two days and is known as "Hunting the gowk". The second day is devoted to pranks involving the posterior region of the body. It is called Taily Day. The origin of the "kick me" sign can be traced to this observance.
Hunt-the-Gowk day falls on the week of April 1 when bairns of all ages play pranks on others then shout "April Fool" at their victim. In this more sophisticated age the practice seems to be dying out but it does remind us that in the past Kings and Nobles all had their Jester or Fool. One of the most famous in Scotland was Aberdeenshire's Jamie Fleeman, the Laird of Udny's Fool. He lived in the eighteenth century and was well known for his wit.
The history of April Fools' Day, sometimes called All Fools' Day, is not clear. There is no first "April Fools' Day" that can be pinpointed on the calendar, although it is known to date back at least to the sixteenth century. Most historians believe that April Fool’s Day originated in continental northern Europe and then spread to Britain.
More about April Fools' Day around the world...
France - French children fool their friends by taping a paper fish to their backs. When the young victim discovers this trick, the prankster yells "Poisson d'Avril!" (April Fish!)
England - Tricks can be played only in the morning. If a trick is played on you, you are a "noodle".
Mexico – the counterpart of April Fools' Day is observed on December 28. Originally, the day was a sad remembrance of the slaughter of the innocent children by King Herod. It eventually evolved into a lighter commemoration involving pranks and trickery.
Portugal - April Fools' is celebrated on the Sunday and Monday before Lent. The traditional trick there is to throw flour at your friends.