Well, you probably won't believe me if I say it's a snake, a huge, child-swallowing anaconda, said the librarian.

A child visits the library with their mum, who tells them to find a book and stay out of trouble. Almost immediately, the librarian warns the child against doing certain things, like climbing the shelves, peeling up the carpet, or taking a particular book. Each time, the child responds with Why not? prompting the librarian to spin increasingly outrageous stories.