Show a deck where verbs and nouns are randomly written onto the backs of a deck of cards. A card is freely selected by the spectator. By combining an action word from a black card and a noun from a red card you can combine hundreds of possible activities. When naming any two cards the spectators will select an activity they should do.
After showing possible different outcomes the named cards are selected. The activity from both cards are showing the sentence: Open the Box!
After showing other possible predictions in different locations, let the spectator open the card box that was in full view on the table all the time: They will find the chosen card as a prediction.
English video instructions, plus written instructions to prepare your deck of cards (any language is possible).