This is a trick where the magician (or ‘Mentalist’) predicts something that will happen in the immediate future.
Some coloured chips or tokens are given to a spectator. A ‘Prediction’ is written and given to another spectator for safe keeping.
The spectator is asked to stack the chips, in any order, following a simple process. When the stack is complete, the ‘prediction’ is found correct … the colour of top and bottom chips of the stack match the ‘prediction’ made by the performer.
The effect can be repeated as often as you wish, with different results at every repetition. A very clever, self working effect, that you can perform as soon as you read the instructions.