This simple trick has a pair of jacks jump from the top of your deck to the bottom!
The real trick is that you have two decks of identical cards. Take the jack of diamonds and the jack of hearts from the second deck and put them on the bottom of the first deck. Now find the other jack of diamonds and jack of hearts, and put those two cards on top.
Show the deck of cards to a friend of yours and pull off the top two cards. Show your friend that these are the two red jacks. Then tap the deck a few times, and pull off the bottom two cards. Voila! It looks like the jacks have lept clear through the deck!