John Wayne made a joke with the punch line "Maam, you ain't gonna get milk out of that kind of goat" in a g rated movie in the 60's or 70's.
And the point is, if the woman is reaching under that kind of a goat, what would she be trying to milk? It doesn't mean she was deliberately trying to do that to the goat - but the double inferrence is there.
Look, folks can agree to disagree on this. But posters are getting viciously attacked for differing. And that's just wrong.
If the joke was the only one of its type, then maybe you'd have a point. But the writer also tossed in comments about Desperate Housewives and going to the Chippendales and dollar bills. So in that context, it is a reasonable assumption that the male horse joke was also meant by the writer to have a double inferrence with a risque interpretation.