It is traditional for people from UK, Australia, New Zealand, South Africa, Ireland, France, Romania and USA to play tricks or practical jokes on each other on 1st April. Children are the most enthusiastic about this custom, but even the BBC and serious newspapers sometimes have "joke" features on this date.
Its origins are not clear, but it may lie on the fact that when King Charles IX of France changed officially the first day of the year from April 1 to January 1, some of his subjects continued using the old system. In any case, All Fools' Day is celebrated to make people laugh. Friends, family members, neighbours, even enemies become targets of all sort of jokes that last all day. If you are an April Fool, just keep smiling, it's healthy!