(I have just finished talking to a group of people at the penguin exhibit when a middle-age man approaches me.)

Customer: “I really love penguins. My wife and I saw some on our trip to Alaska last summer.”

Me: “Oh, did you go to the Alaskan Sea Life Center? I hear it’s very nice.”

Customer: “No, we saw them when we were walking on the beach.”

Me: “Actually, sir, wild penguins only live in the southern hemisphere. What you and your wife saw were most likely puffins. They look very similar to penguins, but they can fly and are commonly seen in places like Alaska.”

Customer: “No, they were penguins. I’m not stupid! I think I know a penguin when it flies right in front of me.”

Me: “Penguins can’t fly, sir.”

Customer: “All birds fly!”

Me: “No, not all of them. Ostriches, for example, can’t fly either.”

Customer: “Ostriches are birds?”

Related:
Bird Brained
Bird Brained, Part 2
Bird Brained, Part 3