I'm going to pretend that I thought of this, even though I was just a collaborator.
On Missing Books:
Person A (a bookseller): Why Can't I find 300 Copies of Book In Question?
Person B (a manager of inventory): They're here, they're just in Overstock.
A: What?
B: It's where we put books that we order too many of, but aren't ready to return yet.
A: Well, can I get a copy. It's for a customer, and he's already pissed. I don't want to tell him we have the book but can't get it for him, even though it's in the store.
B: Well, we could have done, but we can't any more.
A: Why?
B: When we put it into overstock, it was with an additional thousand copies of Last Week's Book In Question, and six hundred of The Event Book We Didn't Sell Enough Of Yet...
A: And?
B: They collapsed.
A: Well, if the pile fell over, can't we just dig out a copy of Book In Question?
B: No, not on a structural level. On a quantum-material-black hole level. They've formed a quantum singularity. The overstock is sucking in books of which we don't have an overstock. The whole collection of books collapsed into a single book the size of The Little Prince. We have a Book Hole floating around the overstock shelves.
A: So, some mad crazy Shrinkage?
B: Ba-dum-bum.
A: So, I should tell the customer to fuck off?
B: I'm afraid so.

Inspired by actual events. Only it was a bad record system and an offsite event. Long story.