[Note: This effect was already part of Mentalism games.]
Effect: A spectator names any card, and you immediately produce it from your pocket.
Or: You write two cards on two business cards, put one in each pocket, and the spectator has to guess at least one of them. (It can be repeated right away if you want).
The method is 100% surefire and practical. There is no math, no probabilities, a little bit of memorization, but it is almost "intuitive". It is not difficult but needs a bit of rehearsal at the beginning, like for everything. It looks casual, completely impromptu, or even improvised, but you will have to do a onetime preparation with current items, which costs nothing. With this, you can do it anytime, anywhere, even to strangers or busy people as it is very fast. Reset takes a few seconds.
It has fooled, repeatedly and consistently, magicians and laymen. It can also be used as an out for other cards or mentalism routines.
1st edition 2015, 11 pages.
word count: 2947 which is equivalent to 11 standard pages of text