Modern Times - Card Trick Magic
The magician shows two decks, one red, one blue, in each hand. The blue card case instantly vanishes and reappears in the pocket. Now the blue cards are tossed on the table and they all change to red right in front of everybody's eyes. In the end, the red card case is opened to find the blue deck there. This transposition of two decks is a great visual effect to use as an opener.