Bank credits $95,000 junk mail check to customer's account (1995)
nytimes.com
nytimes.com
TL;DR Man walks into a bank and deposits a junk mail check to see if the bank would actually cash it. And they did. Then the bank wants the money back.
IIRC he never went to jail because he just "wanted to see what would happen" which is not fraud in and of itself. There was a more detailed article on the interwebs but it's lost to time.