It's called "Fool" by Christopher Moore.
It's the funniest book I've ever read. It's completely sick and obnoxious, and I mean that in a good way.
It's a retelling of King Lear, Shakespeare's most tragic tragedy, but it's told from the point of view of King Lear's fool. If our short bus did Shakespeare, it might come close to this.
From the inset:
"This is a bawdy tale. Herein you will find gratuitous shagging, murder, spanking, maiming, treason, and heretofore unexplored heights of vulgarity and profanity, as well as nontraditional grammar, split infinitives, and the odd wank . . . If that's the sort of thing you think you might enjoy, then you have happened upon the perfect story!"
If you're into reading, please oh please for the love of GOD check this book out.