What is the reason after calling "April's lie"?

Answer 1

In Western countries, April 1 is a time for pranks and tricks; for instance, to say something outrageous in the hope of making another believe it or to play a practical trick (say, by hiding a man's winter coat at the time he has to go out on a cold day). An April Fool is one who falls for such a trick. Among Arab peoples apparently, though I do not know this at first hand, April 1 is the day for telling lies in the expectation that they will be believed by the person hearing them. These range from something harmless to something more serious, such as telling someone that his father has had an automobile accident. The April lie would seem to be an extension of April Fool's Day, which seems to go back to the Saturnalia of the ancient Romans, when wild things were said and done, and to medieval times when a group of people might elect a mock-Pope and practise mock church rituals.