Once you're on the ground, all bets are off. We remove their genitals, forbid them to have social contact with other dogs which pretty much prevents them from having sex their whole lives and we feed them the same crappy food everyday. If they want to hump us every now and then I figure it's the least we can do. I know the red lipstick is pretty gross but it's no worse looking than human male genitalia. So the next time your dog starts humping you just let them. Just don't let "finish" ... if you catch my drift. That would be bad.