As much as I enjoy bathroom humor, I normally don't enjoy reading about fecal matter. However, this book is interesting and amusing at the same time. This book basically talks about different types of poop in terms of shape, size, and color and explains why and how they form to be the dookie types they are. I never even heard of a "stool transplant" until I started reading this book!
So yeah, if you ever wonder why your shit looks weird or if it's normal for you to strain a lot or whatever, check it out! It's about $10 new, but you might be able to find it somewhere used for cheap.
Official Site!