A man walks into a bar and asks for a shot of whiskey. He drinks it and asks "how much?"
"£3" said the barman. So the man reaches into his pocket and takes out three £1 coins. He gets one and throws it to one side of the bar, gets the second one and throws it over to the other side of the bar; and finally throws the last one at the barman.
The barman is annoyed but doesn't say anything.
The next day the same man walks into the same bar and asks the same barman for a whiskey. Again, he takes out three £1 coins and throws the first two to each side of the bar and throws the third straight at the barman, and walks out.
The barman is really annoyed, but doesn't get time to say anything before the man leaves.
The next day the man returns to the bar and orders a whiskey of the barman. The barman obliges and before he can say not to throw coins at him, the man puts a fiver on the bar... and the barman sees his chance for revenge!
So the barman gets two £1 coins and shows the man his change. He gets the first one and throws it to on side of the bar, and gets the second one and throws it to the other side of the bar.
Then the man reaches into his pocket, takes out another £1; throws it at the bearman and says....another whiskey please!!!!