Manspeak for having sex with the
wife.
Some men, especially those who have been married for years,
don't perceive "walloping the donkey" as a pleasure. Instead, it is seen as an onerous, unpleasant and even potentially dangerous chore. Something that needs to be done so that you can get on with enjoying life's true pleasures (i.e. televised sport and
beer) in comparative peace and quiet.