Just for fun drop into Matt's and tell them they spelled it wrong and that you know that it is true because you read it on the internet.
Looks like you got me there!
http://mattsbar.com/
I guess there's a bit of controversy as to who invented it and the spelling...again from the Internet!
The Juicy Lucy burger was invented in a south Minneapolis bar sometime in the 1950s, and depending on who you talk to, that was either the 5-8 Club, who serve the Juicy Lucy, or Matt's Bar, who make the Jucy Lucy, and let customers know that "if it's spelled correctly, you're at the wrong place".