Well, PM deleted a bunch of answers. It says 8 responses and now that I've opened the question, there is only 1.
What? The other 7 answers a bit too truthful?
This is tough.
I mean, try it.
You know the 'mark' isn't really jumping from one finger to the other finger, right?
So, your marked finger has got to be twisted/mangled across or behind your other fingers to achieve the effect.
Again, give it a shot.