April Fools' Day

April Fools' Day, sometimes called All Fools' Day, is one of the most light-hearted days of the year. Its origins are uncertain. Some see it as a celebration related to the turn of the seasons, while others believe it stems from the adoption of the Gregorian calendar.
April Fools' Day prank in Boston's Public Garden
 warning people not to take photographs of sculptures. 

April Fools' Day in the UK
April Fools' Day in the US

BBC Flying Penguins:
An amazing video where you will see flying penguins

How was the penguin prank made? Watch this video:
The making of Penguin April Fools' Day