I might be wrong but it seems like a few years back that there was some kind of limits or "cookie cutter" type sign that people had to use when your car was displayed at SEMA. I don't actually remember looking last year, but I had a friend with a car there and was told they wanted nobody competing with crazy signs. Also see this link and scroll down down to the text below sign. Scott talks about it in his little blog.
http://www.project33.com/article.cfm?ID=760