In case it has slipped your mind, this Saturday is April 1st, or, as is popularly called, Fools’ Day. The origin of this fun day, when pranking people is encouraged, is hazy. Some believe the tradition began in 1582 when the world transitioned from the Julian calendar, which started the year in April, to the currently used Gregorian calendar. Others think it was to celebrate the start of spring. Though individuals often prank each other, it is corporations that really get into the spirit with elaborate gags. Here are a few that were credible enough to fool people for days.