As I remember, which isn't much of a qualifier, it was a book about police and one of the main characters called his backup gun "Roscoe." The name or tern "Roscoe Rules" fits in their somewhere. I know that's not much help, but I can Tell you I named my backup gun "Roscoe" after that. Ask my kids who Roscoe is and they will tell you "It's Dad's little revolver."