A horse walks into a bar and orders a pint. The bartender says, “You come here a lot, do you think you’re an alcoholic? ”The horse replies, “I don’t think I am.” Then the horse disappears.

It's not just a play on what Descartes famously said, “I think, therefore I am,” when the horse answers, "I don't think I am," and therefore ceases to be, it also hints at a terrible (I admit it) pun: Posting what Descartes said first and the conversation at the bar second would be putting Descartes before the horse.

I’m not sorry I posted this. Blame my son, who sent it to me today.