Colour Changing Ball to Jumbo Square

The magician displays a red ball and places it into his left hand. Suddenly, the ball disappears and is found to have jumped into the performers right pants pocket. He places the colored ball on top of his left closed fist and pushes down inside his hand with his index finger. He asks the spectators which hand contains the red ball and no matter what they answer, the spectators won39t be right in the magician39s left hand is a large 3.5 inch red square and in his right hand is a black ball!