Attention to Detail

One day, an employee received an unusually large paycheck.  She decided not to say anything about it.  The following week, her paycheck was for less than the normal amount, and she confronted her boss.

"How come," the supervisor inquired, "you didn't say anything when you were overpaid?"

Unperturbed, the employee said, "Well, I can overlook one mistake, but not two in a row!"