A spectator shuffles the deck and takes a card. A Joker is placed on the table. On the back of every card, a different time (am, pm) is written -- no repeats. The spectator names the chosen card. Immediately, the magician/mentalist knows the time written on the back. The audience thinks that the performer has memorized the time associated with each card -- they are then asked to name another card (NO FORCE). They read the time on the back of the new selection and the performer turns over the Joker, revealing that the time written on the back of the Joker is the same as the spectator's choice. (The Joker has been on the table from the beginning, before any choices were made).
-- This video explains the entire process and secret (you provide your own deck).
-- Schematic photographs (jpg) and explanations are also included in this download to help you master this great effect!