Could have been better phrased ... oh well. Is it true that Americans use or used to use 'fanny' to mean the body part on which one sits, rather than the body part through which females pee and have sex and babies? That's the UK usage, or was, and we mostly use UK here though US usage is moving in fast.
Dick is pretty universal, I think, and so perhaps are
Willie and
Rod. DH
Lawrence used '
John Thomas' in the same way, but I've never heard it IRL.