A man goes to get his salary cheque and when he opens it he discovers that his employer has overpaid him by U$ 2,000. He decides not to tell anybody and keeps quiet. At the end of the following month when he opens the cheque, he sees that he's been underpaid by £2000. Fuming, he goes to have it out with his employer. "Sir, I think you've made a mistake on my cheque." "And how do you figure that?" his employer asks. "It seems I've been underpaid by U$ 2,000." "So?" "No disrespect Sir, but I want my money." "Last month I overpaid you by U$ 2,000 and you didn't complain so why now?" "Well Sir, thing is I don't mind if you make a mistake once but if it becomes a habit I have to say something."