Our intrepid magician goes forth onto the unforgiving streets.
A passing female is asked to take part in a simple experiment...
"I'll riffle the cards before your eyes - watch - think of one card."
The cards are duly riffled - faces towards the helper.
"Have you a card in mind ?"
Our Magician concentrates intensely.
"You could have chosen any one of 52 cards ......"
"You are thinking of a red card............ it's a low number.......... a three.
The card you are thinking of....... is.......... the 3 of Diamonds!"
"Whow, yes yes yes !!"
To perform this miracle of mind reading you will require a 'short card'.
You must shorten any card by about 1 mm.
Place the short card in front of the card which you want to force on your helper.
The 3 of Diamonds is a good card to use as a force card as it easily visible and not difficult for the helper to get a 'fix' on it.
The cards are riffled at eye level and quite close the helpers face. The force card and the short card should be positioned about 2/3 into the deck.
The cards should be riffled very fast ( so their faces appear blurred). When the short card is reached the riffle is paused for an almost indiscernible moment - just long enough for the helper to fix on the force card (3D).
The riffle continues at speed.
With a little performance the helpers mind is read and 'their' card is revealed by the magician.
This feat of magic requires much practice and it is useful if the helper is a little scatter brained or slightly drunk ! You don't want some bright eyed smart alec to pre-select a card thereby ignoring your riffle !!
Good luck with it.