I was at a dinner party and asked someone what they do. They ran a research lab, and I was really interested, and asked questions. He was surprised I actually liked chemistry and was interested in his research. He said normally people just joke about how they hated chemistry in high school, so he normally avoided talking about it. He said people don't realize it's really rude to basically tell someone that their life's work is boring and they hated it when they were 16. I'm now much more careful about how I respond to what people do for a living, even if it's not something that I'm interested in.