Did you forget to take the tinfoil off?

Dr. Bill, my Dad's a pharmacist, and one of his all-time favorite stories is about a guy who came in complaining about the suppositories he just purchased, said they didn't work, and that, what's more, they were just adding immensely to his pain and discomfort. And my Dad said, "Well, did you take the foil off?" and the guy said, "What foil?" I'm NOT making this up!