Attempts At Librarian Humor

I’m in the stacks at the library when I hear a man at the reference desk talking to an employee.

“You’re a librarian so you should know that, right?” he asks slowly.

“Well, there are a lot of things we’re supposed to know, but I don’t think that’s one of them,” the librarian replies, clearly trying to keep his cool.

“No, it’s a joke, man, just answer the question,” the man says.