I did a YouTube search and it seems this is common thing at state fairs:
Iowa State Fair: http://www.youtube.com/watch?v=m4lATZc8RX0
Wisconsin: http://www.youtube.com/watch?v=D4F8ob9nlfY
It doesn’t happen at the Texas State Fair.
When I was in CA in early 2000s, I lived about a mile from the CA State Fairgrounds. It was widely known in the area that the last night of the fair was “beat whitey night.”
Never reported in the media.