The girls in the class were ew-ing when the topic was rats. And the teacher said, "Do you know how useful they are? They are used for various experiments bla bla bla. Whom would you test this on if rats Didn't exist?" So, I said, "How about criminals?" (ok, that was cliche). Suddenly his attention shifted towards me and he said, "How do you define criminals? Whom do you call criminals?"