克也増田時間の冷凍

A magician shows a picture of a pocket watch which is sealed inside a Lucite block. The Lucite block is kept in a transparent plastic cover. A black spot on the plastic cover hides the watch face so that no can see when the watch was photographed. The magician asks a spectator to name any hour. (This is not the magician's choice or a force.) Then the Lucite block is removed from the cover revealing that the watch displays the same hour as the spectator's choice. 

Frozen in Time allows you to predict a randomly selected time with nothing more complicated than a photograph. No electronics, no complicated gimmicks.