Brace yourselves - It's almost April 1st, the one day of the year when pulling a light-hearted prank is not frowned upon. Also known as April Fool's Day, the origins of this fun tradition are a little sketchy. Some believe that the light-hearted fun began in 1852 when the world transitioned from the Julian calendar (which began the New Year in April) to today's Gregorian calendar. Others think it was to celebrate the change of seasons.