A priest, a pastor, and a rabbi are walking down the street on a hot day and are quite thirsty. They pass a busy bar and want to go in and get a drink but have no money. But the priest comes up with an idea that he thinks might work, so he goes in alone, telling to others that if his idea works they can all get free drinks.
He orders his drink, and when he's finished with it, the bartender gives him his tab. The priest says, "But son,... I already paid for the drink!" The bartender says, "I'm terribly sorry father but it's really busy in here and I must have forgotten."
The priest goes out and tells the pastor and the rabbi what happened, so the pastor goes in next. The pastor orders his drink and then informs the bartender that he already had paid when the bartender asks him for the money. Again the bartender apologizes.
Finally the rabbi goes in and orders his drink. Again the bartender gives him the tab and the rabbi tells him, "Son, I paid you when I ordered the drink." "I'm terribly sorry rabbi," says the bartender, "I don't know what's wrong with me, but you're the third man of the cloth that I've done this to."
"I'm sorry son," says the rabbi, "but I'm in a terrible hurry,... Just give me my change for the £20 I gave you, and I'll be on my way!"