Rene Descartes walks into a bar. The Bartender says, ""Hey, Rene, you want a scotch?"" Descartes replies, ""No, I think not."" And then he vanishes. No dice.

So a horse walks into a bar... So a horse walks into a bar. The barkeep seems to know that the horse frequently goes to bars, and he asks the horse, ""Aren't you an alcoholic by now?"" The horse replies, ""I think not!"" and disappears, seemingly into thin air. See, the joke here is based on Rene Descartes' famous philosophy of ""I think, therefore I am"", however, explaining that part first would be putting Descartes before the horse.

Rene Descartes walks into a bar ~~The bartender asks him if he wants a drink.~~ ~~""I don't think so...""~~ The bartender says ""Hey, Rene, gonna have your usual?"" ""I don't think I am."" Descartes disappears. Edit: Fixed it by popular demand.

A horse walks into a bar....... The bartender asks "hey, why the long face? Are you depressed?" The horse ponders for a second, scratches his chin, and says "I don't think I am" and promptly disappears. You see, this is a joke about Rene Descartes' famous statement "I think, therefore I am" and I could have mentioned this at the start of the joke, but *that would be putting Descartes before the horse*.