When I was a teenager I worked at a Shell gas station. Once I had a customer who asked about the advantages of using Shell nitrogen-enriched gasoline. I didn't

When I was a teenager I worked at a Shell gas station. Once I had a customer who asked about the advantages of using Shell nitrogen-enriched gasoline. I didn't know anything about it and found their question really odd. As I recall, they came back later and revealed that they were a secret shopper for Shell, and we failed the random inspection. All because of a question that no real customer ever asked in my experience. ;-) My boss didn't care, fortunately.