I once was eating in a diner with my girlfriend at the time. We had finished our appetizers and she said she was full. I said I was as well, and we should go. She looked at me quizzically, and I explained that if you are eating in a restaurant and you are full before the main course comes you are allowed to leave and not pay. She looked at me like I was crazy, but I said it so earnestly and acted like she was insane for NOT knowing this rule. After a minute or so she actually believed me and went to put on her coat. I almost died laughing. She was especially annoyed when I told this story in her presence any chance I got.