Andy Nyman - Big Reaction

They are told that if the magician gets the effect wrong, they can "Boo" him and if he gets it correct, they can all "Go Crazy" with cheers and applause.
The magician then goes thru the face up deck and finds the card that was named and it is placed aside.
The backs of all of the other cards are shown to have the word "Boo" written on the back of each one. The attention is returned to the chosen card and in a different colored ink, the words "Go Crazy" are written on the back of the chosen card.