Every year on April 1, April Fools' Day is celebrated in many countries around the world. In France, it's called Poisson d'Avril or "Fish of April." In Scotland, the holiday is often called "Gowkie Day." In Iraq, the holiday is called Kithbet Neesan or "April Lie." History experts say people have celebrated April Fools' Day for a long time. Some believe the tradition comes from the ancient Romans more than two thousand years ago. It was a day of playing games and pretending to be someone else. Others say the day for fooling began in France in 1564, when King Charles changed the yearly calendar . He moved New Year's Day from April 1 to January 1. Many people did not know about the change because of communication problems back then. Some people continued to celebrate New Year's Day on April 1. Other people called them April Fools and played jokes on them. In the United States, April Fools' Day is just a day of joking and playing tricks on friends. These kinds of jokes are also called pranks. These jokes typically end in the prankster shouting "April Fools'!" Simple pranks, like telling a friend a funny lie or making prank phone calls, are still common. But, major companies also get in on April Fools' Day fun in a much bigger way. A few years ago, on April 1, Starbucks announced it was introducing new coffee cup sizes -- Plenta and Micra. The very large cups, bigger than a human head, remained useful for customers even after finishing all that coffee. According to Starbucks, the cups could be used as a rain hat, a pot for plants, or a lampshade . It did not take long for customers to catch on to the prank! More and more, people use social media or smart phone apps to play pranks on their friends on April Fools' Day. One very annoying smart phone app, Cat Facts, sends funny facts about cats to your friends' phones, every day. In the United States, April Fools' Day is  _  .
a day of joking and playing tricks on friends. a day when you can play jokes on any people. a day when people can't shout "April Fools'!" a day when Starbucks introduced new coffee.