A man goes into a bar…
…and orders a beer. The barman gives him a beer and tells him that it is on the house.
When the man orders a second beer, he tries to pay but the barman refuses to take his money.
This continues for well over an hour, and the man realizes that the barman isn`t charging anyone for the drinks.
Finally he asks the barman why he is giving all the booze away for free. The barman answers, “I just found out that the owner is having an affair with my wife. So I am doing to his business what he`s doing to her.”