Allow the audience to watch as you extract four cards from the deck: the kings from every suit (heart, diamond, club and spade). Hold these four cards face down in the thumb and middle finger of your right hand as you use the rest of the fingers of that hand and your left hand to straighten the cards of the deck. These cards should be face down as well.
Tell your audience that you are going to put the four cards in the back pocket of your jeans or pants. Make a show of reaching behind you, and, as you do so, slip all but the four kings inside the pocket. Do your best to hide the exact number of cards in your hand and obscure them as much as possible as you hold them.
Bring the four cards before you, still face down, and place them in your left hand, covering them with your right. When you have your right hand over the cards, hold your fingers in such a way that it appears the deck's much bigger. You'll have to curl your fingers a bit without revealing much. Make a show of drawing the fingers of your right hand to show the backs of a few cards one after another, then push them forward against the curled fingers of your left hand, stacking them again. Cover the cards with your right hand, saw a few incantations, then open your hands and reveal just the four kings.