Black and White Chips

In one hand, you have a white disc, and in the other hand a black disc.
You close both hands, and when you open them, the white chip is now black, the black one now white.
Then you close your hands again, and the discs go back to their original colors.
Amazing!
But wait a minute... It becomes obvious to your spectator that you are only turning the discs over in your hands, that they are each black on one side and white on the other.
And that's when the magic happens!
Place the two discs together, and suddenly one disc changes to YELLOW and the other one to RED!
But that's not all!
If they think all you did was turn them over, flip the red disc over to show the other side.
It's not white or black- it's BLUE!
And flip the red disc over- the other side is not white or black, either- it's GREEN!
Startling and easy to do!
Best of all, your hands are left COMPLETELY EMPTY- there is nothing left to hide!