A guy and a horse walk into a bar.
The guy says to the bartender, "I'll have a beer."
Then the guy goes "I'll have a few more, pls."
Then the guy is drunk. He gets on his horse and decides that he's too smashed to continue riding his horse, so he uses his ATM card to let him into the lobby of his local bank, where he proceedes to park his horse and take a nap.
The punchline of this joke is that the horse crapped inside of the bank.