Checkers and Rally's, purchase an order of fries of any size can receive a free Big Buford.
I'm not sure if this is a local thing or not, but Rally's is currently having big bufords for free when you purchase any size fry. It seems like an incredible deal that no ones talking about. I have seen the signs advertising this deal near me so it may be YMMV.
Unfortunately I can't find any links other than the TV commercial.