I was remembering this morning the old practice at Frankfort Camp meeting of taking a "free will offering" for meals on Sunday. Since we didn't believe in buying or selling on the Sabbath (understood to be Sunday), they didn't believe in buying or selling food on Sunday during camp meeting. On the other hand, people had to eat, didn't they?
The answer was a solution the ancient Pharisees would have been proud of (and you have to know that I don't mean that with the bias many would--the Pharisees were not the stereotypical boogie men they are often made out to be--they were just good at finding ways to do things within the rules rather than just making exceptions in certain circumstances). The people who worked in the kitchen were volunteers, so no one was paid for working on Sunday. Meanwhile, the Sunday meal was a free will offering. The normal amount was posted, but not required.
So in theory, you could have eaten for free on Sunday. But with conscience clear, most people just paid the suggested amount. And to be honest, they would have felt like they were stealing if they hadn't. :-)