This is the rubber band finger-switch trick. This is a magic trick in which a rubber band "teleports" from one pair of fingers to another. Don't worry, I didn't simply use my other hand to transfer the rubber band. I first learned this trick from a classmate of mine in school. In the steps that follow, I will teach you how to perform this illusion.
Step 1: Materials
The only material you will be needing is a rubber band. Make sure that the rubber band doesn't have a small enough diameter to where your blood circulation cuts off.
Step 2: First Rubber Band Positioning
On any hand you choose, make the rubber band surround only your index and middle fingers.
Step 3: Setting Up the Trick (1/2)
With the rubber band still surrounding the two fingers, pull the rubber band with at least two fingers from the other hand. Do not pull the rubber band too hard, as it might break. Next, twist the pulled portion 180 degrees in either direction. Then, make the twisted portion surround the same index and middle fingers.
Step 4: Setting Up the Trick (2/2)
To finish setting up the trick, pull both strands of the rubber band enough so that you are able to make it go around the segments of your fingers farthest from your knuckles (excluding the thumb).
Step 5: The Result
The first image is a view from the back of the hand. The second image is a view from the palm of the hand.
Step 6: Carrying Out the Illusion
Make sure the front of your hand is facing the audience, as shown in the first image. To carry out the illusion, extend the fingers of the hand on which the rubber band is on, excluding the thumb, as shown in the second image. While doing this, keep the back of your hand facing the audience. The switch has been made!