A horse walks into a bar and orders a drink.
The bartender, noticing the horse as a regular, asks "buddy, you're here every night, do you think you're an alcoholic?"
The horse responds "I don't think I am", and promptly disappears into thin air.
You see, that was a play on Descartes parable "I think, therefore I am".
I would have told you that earlier, but that would have been putting Descartes before the horse.