This also made me think of when I had to certify some certificates of mine at the Police Station, how the gentleman who assisted me kept on saying that "you owe me" for certifying all my documents.
(OK, so I actually thought it was your job? ... anyways he was taking chances by pulling my leg 'cause I'm a woman).
He kept on going until he got to my certificate where it states that I am qualified in handling venomous reptiles, that he actually got such a huge fright that he said ""What's this?!". So I told him with which animals I work and his eyes got as wide as saucers and he said "Don't worry, you don't owe me anything. It's free".