Start out by telling a story of four king thieves (have the Kings separated from the rest of the deck). One day the kings decide to rob their local Famous Store. The four kings fly their helicopter to the roof and begin to devise their plans. (As you say this, place the four Kings on the top of the deck.)
The first king says, "I'll take the clothes from the first floor" (Place the King on the bottom of the deck). The next king says, "Okay, I'll rob the second floor (Place the King
somewhere in the middle, but near the bottom." The third king says, "Then I'll rob the third floor (Place the King somewhere above the second, but not on top.) The fourth king says, "I'll be the lookout. If I see some police coming, I'll whistle and you should all come up to the roof."
The kings begin to rob the store. However, the king on the roof sees the cops are starting to surround the store. So he gives the whistle (whistle - or scream or something, if you can't whistle) and the four kings all run up to the roof and fly away in their helicopter to safety (take the four cards off the top, one by one, revealing the four Kings!)
How it's done:
The whole trick is done right at the very beginning. Along with the four Kings you place on the top of the deck, you also place three other cards on top of those. When you show the Kings, keep the others hidden behind them, so it looks like there's only four Kings. When you put these together and put them on the "roof," and then move the three Kings to the various parts of the building, you're actually moving those three cards.