My favorite was a giant cut out of Grand Pa Simpson. There were no words. It was just a cut out of him.
The sign was present at the Kansas-Missouri game in 2007. The two fan bases were separated and it was on the Kansas side.
It was awesome because there is one episode in the series where Grand Pa Simpson randomly throws in a line "It will be a cold day in hell before I respect the state of Missourah! (something like that at least). It was brought up because he had a flag in his house with only 49 stars. Being a long time Simpsons fans I just couldn't stop laughing at the subtle joke by some Kansas fan.