A horse walks into a bar.
The bartender looks up and says, "Hey, why the long face?"
The horse replies, "I just lost my job, my wife left me, and I'm about to be evicted from my stable."
The bartender, feeling sympathetic, pours the horse a drink and says, "Here, this one's on the house."
As the horse takes a sip of the drink, a man in a lab coat rushes into the bar. He exclaims, "Wait! Don't drink that!"
Everyone in the bar turns to look at the man. The horse, startled, asks, "Why not?"
The man in the lab coat reveals, "I'm a scientist, and I've just discovered that we're all characters in a simulation. This entire joke is just an elaborate experiment to see how we would react to unusual situations!"
The horse, the bartender, and the rest of the bar patrons stare in disbelief, finding it hard to believe that their entire existence is merely a construct for someone else's amusement.