Ever read a book that should have been philosophy, but wasn't?

This is pure left field, folks- but my fave book in this category is actually shelved in humor. I wondered if anyone else had a random moment of enlightenment in the section they would least expect. My pick?

The Hedonism Handbook

Off the wall, yes, but also a significant diatribe on how American culture makes us "become" happy instead of just "being" happy. Oddly enough, led me into a lot of meditation and spiritual readings.

What surprised you like this?

The winning investment habits of Warren BUffett and George Soros.