To let the Federal Government and all liberal/Commie butt sniffers know that "We the People" reserve our God given right of freedom of speech, and that we reserve the right/duty to rebel when the Government becomes abusive of our inalienable rights "among these are life, liberty, and the pursuit of happiness." The Founders would expect no less of us.
Well, I suppose something along those lines might have been my fourth or fifth guess. "Yankee Go Home!," "States' Rights!" and "I Hate N*****s!" tend to be the top three, the order and probability of each option being influenced by the bigger picture.
Next time I see a CBF, maybe I should consider any of those four messages is possible. But, that's just because you took the time to explain yours.