Just cross your arms, smile wryly, and comment on how pathetic the Interviewer's pen is. Cheap material, runny ink, a grip that's painful to hold. Wish him good luck in taking notes on subsequent interviews.

Then lean in, and say "But, you know? I've got a premium writing utensil. It's crafted in the Netherlands by a Space Age engineering firm. It's designed to fit comfortably between your fingers. And the Indian ink that runs through it glistens and glides smoothly through a specially crafted tip."

Pull out a business card with absolutely beautiful handwriting on it. Just as he expresses surprise and interest, sigh and say "But... It's really not for you. It's really more of a thing for your boss, or your boss's boss."

Start getting up to leave, and wait for him to come running after you.