- Riddler: What is it that walks on four legs, then two legs, and finally three legs?

- Doctor Young: A human being. As a baby it crawls on four legs, as an adult it walks on two, and in later years it uses a cane.

- Riddler: Good try, but the answer to all three is a baby. True, it crawls on all fours, but cut off its legs and it can only wiggle on two limbs. Give it a crutch, it can hobble on three. You see?

- Doctor Young: That's horrible. How can you even joke about that?

- Riddler: Easily, doctor. It's not my baby.