April Fools' Day is one of the jollies and funniest holidays of the year, of course, if it's you, who plays harmless prank upon someone else. This unofficial holiday is known and admired in many countries, and it's annually celebrated on April 1.
Fossil Fools Day is an annual environmental campaign that coincides with April Fools' Day. It aims to raise awareness of the hazards caused by harvesting, processing and utilizing fossil fuels.
April 1 is Edible Book Day. This is a very unusual holiday, that is celebrated around the world since 2000.