Someone showes me two envelopes. I one of them he has put some money, in the other one twice as much. As the rules of the 'game' he playes with me, go, I am entiteled to keep this envelope or switch to the other one.
Someone writes two different positive integers on two sheets of paper.
I take one of them. As in the game before I am entitled to switch once I've read the first paper. I win if I get the paper with the larger number.