April Fool's jokes have been a staple for company ad departments, and the bane of financial journalists, for more than 20 years.Taco Bell (YUM) could be considered the forefather with its "Taco Liberty Bell" joke that took out full page ads announcing the rebranding.That sparked a lot of initial outrage, but also an estimated $25M in free publicity and the No. 7 spot on list of top 100 April Fool's Day pranks of all time from the Museum of Hoaxes.This year's big prank missed the mark, though, not least of all for its timing.Volkswagen (VLKAF) sent out a press release on March 30 confirming that it was changing the name of its U.S. operations to Voltswagen after reports of new branding.But it soon had to backtrack and apologize to investors and consumers, saying it was an early April Fool's joke."Volkswagen of America developed and implemented a marketing campaign to draw