It's a funny song in a classically black humour way, but only because to contempory ears, it demonstrates such regressive attitudes of the times and of the people it describes - in which the content itself may indeed have once been considered funny.

The reason it was probably considered funny then, is to my mind, very didfferent to why it might be funny now.

Once, to many people the idea of severe child or spouse beating was a normal everyday occurrance. They were the people who were desensitised to their own behaviours. So maybe it was funny to them in a 'bawdy' way.

To my ears, the song is more like a kind of circus freak-show of grotesques. And has the effect of conjouring up equivalently freakish and very black-humour style images of duelling banjos, village lynchings, incestuous inbreeding, and nine year-old brides...