The Effect
The magician tells the audience that he can bend a playing card placed on the back of his hand without even touching it. This the magician apparently does in full view of mystified spectators.

Method
Before you place the card on the back of your hand, you need to moisten your skin and this can be achieved by your pretending to wipe your nose with the back of your hand and discreetly spitting on or licking this area of skin.

When the card is placed on this moistened area of skin then the combination of the warmth of your hand along with the moisture will cause the playing card to magically bend much to the amazement of your audience.

This is a very simple card trick but it is nevertheless quite baffling to spectators.