Assume there is a machine that is giving out unique numbers per person. If person A presses the button twice, they get the same number they got previously. If p

Assume there is a machine that is giving out unique numbers per person. If person A presses the button twice, they get the same number they got previously. If person B presses the button, they get a different unique number. Now, I searched for a long time to find a person who is not A, but will get the same unique number as A. So now your wife can agree that the machine does not provide unique numbers per person and is, thus, broken.