We burned a library book once, by accident. There was a reptile heat lamp on a timer involved, the whole situation was very messy. I was new to parenting, and took the remnants of the book to show to the librarian, and tearfully confessed my family's carelessness and vandalism.
Now when these things happen, I just say, "Yeah, that one won't be coming back, how much is that gonna cost me? And what's the total with my late fees? Okay, I'm pretty sure I have $57.34 on this card, let's give it a whirl, shall we?"
What kind of reptile did you have?