The mysterious case of the never ending library fine

Over the past 4 years I have probably paid somewhere around $150 in library fines. Okay okay so it's not really a mysterious case. It's actually quite clear why I've accumulated such a large fine. Somehow I have managed to lose various textbooks and library books, and other times I just keep books checked out for months at a time. But just when I thought everything was paid for (I just bought a book last month for $20), I get a phone call informing me of more fines. Now that is the mysterious part, because what more can they charge me fines on? I've already purchased half the library. Today I'm going at break to crack the code, solve the case of the mysterious fine...maybe they will name a part of the library after me