Now that I think back on the last several weeks, people will cite references like the Forrest escort - Polebearers speech as authentic sources. When you respond that this isn't good evidence, they ask for your sources to "prove" there were no black men in Forrest's escort. Of course no one can prove a negative assertion ('when did you stop beating your wife?), so they feel like you're pinned in their game of chess: they have a source, and you don't don't, plus you can't "prove" black men were not in Forrest's escort.
End of discussion.