The book by Roach, who has also written nonfiction, science-oriented works such as "Packing for Mars," focuses on the digestive system and how it functions 鈥 not a topic you would expect to be described as humorous, but Nelson says she was completely won over. "She's so quirky and weird as a writer," she said of Roach. "She's writing about pretty basic bodily functions and she's hilarious."