Whatever the prank keep it safe and fun for everyone. The trickster usually ends it by yelling "April Fool!" also known as All Fools' Day- although not a federal holiday, it is a holiday observed on April 1, each year since 1562. It is a day which celebrates the custom of playing practical jokes on friends, or sending them on fools' errands. Sometimes, elaborate practical jokes played on friends or relatives might last the entire day and even the news media and major companies sometimes get involved.