Bookman!

"Y'know that little stamp, the one that says 'New York Public Library'? Well that may not mean anything to you, but that means a lot to me. One whole hell of a lot."

Lieutenant Bookman, in the Seinfeld episode "The Library"

Life imitates Seinfeld, as librarians in Queens, New York, get tough with scofflaws:

Late Library Books Can Take Toll on Credit Scores (New York Times)