My friend Ignoto is lately back from DC where he stopped at an oyster bar. As they were blissfully composting their lunch, a server showed up with a try of little chocolate bits and said, "we don't do dessert, but these are on the house."
Say, what? It's an article of faith that dessert (next to booze) is where you make the money in the restaurant trade. What gives with giving it away?
Best guess? There's so little work in preparing an oyster that the oysters are a profit item all in themselves. The chocolates are to get you out of there. Like the waitress in bobby sox who noisily refilled your coffee cup to get you to say "no thanks, I've had enough."