The 2 card monte trick is a truly baffling card trick and was performed on one of the David Blaine TV specials. As a card magic performer, you need to be very comfortable with the double lift to try this effect.
David Blaine shows a spectator the Queen of Diamonds on top of the deck and then tells them to hold the queen face down in their hand. He then shows the next top card, the Queen of Hearts. After a few confusing switches of the cards, the spectator is told to guess which Queen is where? When he turns over the cards, he realises he is holding no queens at all but instead – 2 Aces.
This card trick requires a fair amount of practice and is really for advanced card magicians only.
Preparation: Get hold of a regular deck of cards and before performing this card trick, put a black Ace on the bottom of the pack, preferably the Ace of Clubs, as it tends to be less conspicuous. On the top of the deck, place the Queen of Diamonds, then the Ace of Spades, then the Queen of Hearts.
Performance: With the deck pre-arranged as described above, first show the spectator the top card (the real top card!) then tell them to hold it in their hand, face down. Next tell them to look at the card they have, so they are sure that there was no trickery involved.
This is a distraction allowing you the time to prepare to double lift the next two cards whilst they glimpse their card. Next, effect the double lift, and using it, show them the Queen of hearts with the ace of course hidden. Place the cards back on top of the pack, then remove the ace, naturally without showing them the face and make a jokey pretense of switching the cards a couple of times then say something along the lines of: ” Are you sure which Queen is which? OK I’ll help you sort it out! “
However, on this occasion, effect the switch very slowly, and really do switch the cards. (try to make sure that they don’t look at the ace in their hands) then, very quickly and as discretely as possible, take the Queen of diamonds which you are holding and place it on top of the deck. Next, “steal” the card off the bottom of the deck (Ace of clubs) and hand it to the spectator, asking them if they can now tell you which is the Queen of hearts. David Blaine effects this card steal incredibly smoothly and with terrific misdirection at 1′-12 in the above video showing his superbly honed skills as a card magician. When they’ve had a guess, ask them to turn over their cards and they are sure to be stunned to discover that they are in fact now holding 2 aces!!
Here below is another video showing a slight (possibly easier) variation and on the same 3 Card Monte card trick. There is also an excellent explanation following the performance of the trick which should help you thoroughly learn it. The main difference with the David Blaine performance is that unlike Blaine, the main card switch is effected from the top of the deck in this video and accordingly, the set up is different.