What cookbook do you own that people would be surprised at?
I've got two. One is the Gilligan's Island cookbook. No, it's not about making generators from coconuts and seawater, it's a collection of recipes (allegedly) from the cast members. It was a gift.
The other is the Back of the Box Gourmet which isn't as horrible as it sounds. It's got the original and current Toll House Cookie recipes, for instance. It's more about cooking with ingredients than it is about mixing vanilla into Cool Whip.