I actually haven't, but I would imagine it might be along the same lines as Monty Python's Penis song from the Meaning of Life - I just love Eric Idle - anyway - My Father told me (yes I talk to my parents quite a lot - but I don't have to listen to them any more so I guess it's okay) and he said that the main reason is because "down there" kinda looks like a gapping wound and the fact that it bleeds on a regular basis doesn't help matters much. He thinks it has something to do with making the silly thing not sound so ... threatening. Which is why most of men's names for their John Thomas are usually something to do with a weapon - what else would you stick in a wound?