It was started 7 years ago by Jeff Rubin, a newspaper publisher and former reporter. He created the holiday because he was frustrated with the errors found in newspapers.
The holiday was on August 22 during the first 2 years because that's Rubin's birthday. It was moved to Sept 24 in 2006 so it could be celebrated during the school year. He also chose that day to honor his favorite baseball player, Willie Mays.