As an acronym, I'm not sure. However, a book (of business) is internal slang for the value of all assets under management (AUM) that a person/group handles.
Bob: "What's the size of you're book, John?". John: "I have $75 Million AUM."
TWIP Book stands for The World and Its People Book! The word "and" doesn't go with TWIP but it goes with, The World and Its People Book!!!!
Holy Moly!!!!