A coworker and I stopped at a Perkins restaurant for lunch on a recent business trip. After we finished our entrees, the waitress took our plates away and asked us if we had saved any room for dessert. I wasn’t interested, but my coworker asked about the cookies he’d seen in the display case on the way in.

“We have a special on those,” the waitress told us. “If you buy three, you get three.”

We looked blankly at each other for a couple seconds, both thinking the same thing: What’s so special about that? If you pay for three, you ought to get three.

Then the nickel dropped. What she meant was that if he bought three, she would give him three more. It was a two-for-one deal.