We had the window cleaner in the other day, a nice chappie who cleans all the windows in the house for a fixed amount. We get him in once or twice a year. He did his bit, and after settling with him, I showed him to the door. On the way out he says: You've written a book, haven't you? Is it already available?. That came very unexpectedly. :-) It turns out he'd heard it from another of his clients. He knows his clients.