Good books that fuck with your mind? I haven't read a book all the way through in a while so I'd prefer if it wasn't a hard/long read.
Ficciones
The Double - Dostoyevsky
Depends. Once I was reading John Dies at the End, and I was walking home in the dark, and stepped on a rotted pear. I jumped, immediately assuming it was a rotted body part.
So. You know. Any book you get really involved in.