You show a black hat and place it on the volunteer's head but you need the hat to be any color but black to make the trick to happen, so you turn it inside out. The hat now changes to a red hat. It still doesn't look right to

Six cards are placed facedown on the table. A spectator freely chooses any card. When the turns his card over, if it has a red dot, the remaining cards are shown to have a blue dot. It does not matter which card is selected--it is always the odd color!