Everyone's seen a film that makes you wince, but have you ever been really shocked by a book?

My candidates:

Wetlands, by Charlotte Roche
Just finished this, and it's bloody disgusting. Literally, bloody - full of blood, spunk, piss, shit, "ass piss", and vaginal "slime". Revolting, in a strangely tender way, as a bloke I felt like a horribly grotty voyeur reading it.

Crash, by JG Ballard
Obvious really, but the ideas and imagery in it are still completely horrific. Brilliant book.

Lolita, by Vladimir Nabokov
I think the surface shock value has been eroded by time and its elevation to classic status, but it's a hell of a brave book.