Then, when our friend entered the exam, he found a surprise: there were no questions about what he had studied about birds. All of the questions were showing pictures of birds' legs, and the student should be able to know the name of the bird from its legs. So our angry friend goes up to the teacher, shouting "This wasn't on the study list! You can't test us on this!", and he returned his paper without writing anything on it.
Later on, the teacher noticed that the student didn't write his name, so he called him up and asked him: "Where is your name, boy?"
Automatically, the boy raised his pants to his knees and said, "Why not find it out from my legs?"