No one knows the specific origin behind April Fools' Day or why Western countries for hundreds of years have celebrated each April 1 with practical jokes and hoaxes. One thing is for sure: it's a day to keep your wits about you.

Newspapers run fake headlines and websites post ridiculous stories linking people who hate each other in matrimony or "exposing" celebrities as aliens from outer space. Co-workers send each other startling e-mails, have toy cats sent special delivery to friends who hate cats or pretend to have just been promoted to chief executive in charge of diddly squat (slang for "nothing").

You might find paperwork glued to your desk or a memo containing the forged signature of your boss demanding all workers dance to disco music every day at 2 pm, starting from April 1. You might receive a love letter from someone who doesn't exist.

April 1 - also referred to as All Fools' Day - is also when you want to look carefully before you take a bite of your lunch. There might be a toy spider in your rice.

The best April fools' jokes are those that actually fool people, like the time Burger King announced the introduction of hamburgers for left-handed people or the fake announcement that Apple had just bought the Beatles. Both hoaxes fed rumor mills for weeks.

Last year, the Sun newspaper in Britain advertised a new "scratch and sniff" edition - and some people actually tried to smell their newspapers. This year, reports are already spreading that British media will make the upcoming royal wedding the target. Will a church be built on Mars for the festivities?

Editors at museumofhoaxes.com recently listed their favorite April Fools' Day hoaxes. Among them is an announcement in the mid-1990s by Taco Bell, the Mexican fast-food restaurant chain, in which it claimed to have purchased the famous Liberty Bell in the United States and planned to rename it the Taco Liberty Bell. There were several angry phone calls from people who apparently don't like tacos.

In 1995, Discover magazine announced the discovery of a new species in Antarctica called the hotheaded naked ice borer, according to the website list, while in 1976, a BBC Radio program reportedly announced that when Pluto passed behind Jupiter, the event would lessen Earth's gravity. Listeners were encouraged to jump into the air to experience floating. Apparently, many callers responded that they had tried it and liked it.

On other occasions, a Tokyo zoo reportedly announced it had discovered a new species of penguin that liked to eat soy sauce; a British publication revealed the existence of flying rabbits, and a US newspaper in Florida reported the discovery of a talking pelican. According to the mock report, the pelican was not that bright, having looked at a dog and called it "kitty".

On the Internet, Google reportedly announced the bogus addition of a translation application for animals. Software maker Avanquest also supposedly announced the sale of a "perfect kiss" simulator, complete with computer screen wipes, to practice the art of smooching.

In fact, the holiday has become so popular that Beijing has got on board this year, too. The capital has no fewer than five April Fools' Day events, including a reading of ancient and modern hutong jokes at The Bookworm, a calligraphy with crayons contest at the Embassy Circle Inn and Tavern and an all-day Festival for Foolish Foreigners at the Sanlitun Village. For tickets, visit ifooledyou.com.cn.

The author is a copy editor for Chinadaily.com.cn. To comment, e-mail metrobeijing@chinadaily.com.cn. The views expressed here do not necessarily reflect those of METRO.