This effect is both humorous and surprising, and captures your audience right away with the familiar character of Pinocchio. You explain that his nose grows every time he tells a lie, and as you are talking the nose visually grows longer. Your audience will be suspicious of the picture, so they are doubly shocked when you remove the picture from the frame, and allow them to confirm that it is nothing more than a single sheet of printed paper.
Show a picture frame to your audience. The picture in the frame is an illustration of Pinocchio. When you make a magical gesture, Pinocchio's nose visibly grows longer, and then shrinks back to its original size. When you remove the picture at the end of your performance, there is only one picture inside the frame, and it is examinable by your audience. They will be unable to find anything unusual with the illustration, even though they saw it altered in front of their eyes.