The Electric Koolaid Acid Test. The first few pages are mainly just descriptions of the elaborate acidhead outfits characters are wearing, and I felt it was going to be one of those books like American Psycho or Inherent Vice which is mainly just a catalogue of cultural tropes and fashion trends from a period of time which I could not personally relate to.
The Critique of Pure Reason. Without a doubt the most difficult thing I’ve read or will ever read, and also one of the most self evidently genius works in the English language. Fundamentally changed my perception of reality, as good philosophy should. It took a solid year of university level philosophy education just to be ready to read page one.