Old monastic curse on book thieves:
For him that stealeth, or borrow and returneth not this book from its owner, let it change into a serpent in his hand and rend him. Let him be struck with palsy, and all his members blasted. Let him languish in pain, cry aloud for mercy, and let there be no surcease to his agony til he sing his dissolution. Let bookworms gnaw his entrails in token of the worm that dieth not, and when at last he goeth to his final punishment, let the flames of hell consume him forever.
That is all.
Stolen from
The Society For Librarians* Who Say Motherfucker.