Doing it right
The meatball sub at Rebel Subs was quite tasty. Ad added benefit was that it was "free", being the 9th such lunch at their shop. So I handed over the full customer card which had the eight punches for half sandwiches and and one for a whole sandwich. Instead of burning the extra punch, and without being asked, the proprietor took a new card, transfered the unused punch to it and sent me on my way. Customer service the way it should be.