The magician takes out a deck of cards that look quite strange. A red deck of cards inside a red card case is crossed by a blue deck of cards. He pulls out the blue deck and proves it to be a full deck. Then the performer pulls out the red deck from the case, which also turns out to be a full deck of cards.
Strange indeed! How on can an entire deck of blue cards be added to a deck of red cards and still fit within a card box?