My alma mater has banned signs from sporting events. I don't really have a problem with this, sportsmanship is a good thing. But from what I remember of UVA sporting events, the most incendiary messages weren't on signs -- they were on t-shirts*. Every time a big rival came to play, they'd sell tshirts on the lawn with mocking phrases. My favorite was the super classy one that said "Juan Sucks" on the front and "Dixon Their Mouths" on the back.
*And that hateful "not gay" chant during the good old song. But thankfully that's pretty much gone away at this point.