I can do that.
Now try this; place your hand in front of your face, with your four fingers (excluding the thumb) straight and closed tightly together. Then, separate your first two fingers from your last two fingers (pic shown below). Now, try and join your middle finger and ring finger together without making your index and little finger move out of their place.
Once that's done, without moving your index/little finger again, place your middle/ring fingers back where they were in the below picture. Repeat for as long as you want.
The only person I know who can actually do it without moving their index/little finger is me, so far.