I've heard Harold Zapolsky's joke a number of times and, although the details change, one thing is consistent. The mohel or mohels always keep clocks in their window. Why? My first instinct was the similarity between the word "clocks" and the actual subject of a circumcision. Here is Harold's theory: "I don't really think there is a connection. The businessman needs to have some item repaired to set up the joke -- and what is more obvious than a watch -- and that, of course, leads naturally to a shop with watches and clocks in the window. This joke was first told to me by the wife of one of my grad school professors, at a student party sometime in the late 50's. At the time, it was considered to be highly risque! "O tempore, o mores" (translation: "The times, they are a-changing.")" Less