Code Book 4.2-w00t-M3nitH3nTehH3rb!!-:-D
Revision C1@P-
p:-KlAp-(5)
It's the one with the pumpkin colored cover.
If you don't have one, the office in Mont has them on the counter under an arrow shaped sign that reads SECRET CODE BOOK.
The office is next to a red and a yellow door. Don't go in those unless you want an argument or contradiction session (can't remember which is which.)
It's definitely to the left of the Ministry of Funny Walks.