I voted for the cane but my first choice was not on the list: Leather strap.
My psychotic girlfriend had a preference for a paddle that resembles a ping pong paddle but the thickness of the wood is much more pronounced. It causes much more pain, per swing, than the leather belt and she gets tired swinging the belt and not getting the desired effect. Mind you we haven't played in some time and she doesn't want to put me in a hospital or a morgue for that matter while I still have a positive balance in my bank account.
Dannyboy