I am reading a book by Peter Mayle, Provence A-Z, which gives a version of the origin of to fanny. To fanny someone in petanques is, as I said, to beat someone 13-0. A kiss from the waitress of the local cafe was the consolation prize for the unfortunate loser of the game. The original site of the kiss was the cheek, but the target changed to altogether different cheeks. A similar version appears on the attached web site.
Not many people know that. Probably not many people want to know that.
I must get one of those plaques.