Burger King Mix & Match - 2 for $6 - Whopper, Original Chicken, or Fish Sandwich
Spotted a poster at Burger King advertising a "Mix and match" deal where you can mix and match two sandwiches from a choice of Whopper sandwiches, Original Chicken sandwiches, or Big Fish sandwiches. It was advertised as any two for $6.00.
Pretty sure this should be available at all franchises, but again, I don't know if it's early days since it was just one sign and I've seen no other advertisement elsewhere.
TL;DR = YMMV