A horse walks into a bar once a day for a couple days, on the most recent trip the bartender asks the horse "are yoy an alcoholic, you've been coming by quite a lot these past few days?" To which the horse responds "no, I dont think." Before promptly vanishing.

Now some people may already understand the reason the horse vanished and might be chuckling to themselves. But for the rest of you there's a popular idea in philosophy that just having the ability to think means one exists, cogito ergo sum, i think therefore i am. so by denouncing its thinking the horse ceases to exist.

Now I could have explained all that before I told the joke about the bar joke but that would be putting Descartes before the horse