Feuchtgebiete (English title: Wetlands) by Charlotte Roche.
Do not pick up this book if you are even slightly prudish. Even I found myself blushing reading it, and on the train I felt like I'd just been caught looking at porn by the old woman across from me. It's REALLY in-your-face bodily functions, WITHOUT being erotica.
here's an English
review Despite, or actually probably because, it's completely full of taboo subjects I'm enjoying it. I really like that it's not written as erotica (I'm a fan of erotica, but it's cool to see someone cover the same subject matter without resorting to just trying to make you horny).