This is an impressive, yet nearly useless skill. It involves performing spinning or flipping a pen using two or three fingers. Good practice for improving your manual dexterity.
The most common trick I have seen is the normal 360 degrees around the thumb. It is usually the first trick people learn.
Thus to do it:
Hold the pen horizontally with your thumb, index and middle fingers, towards the end of the pen (pencil, whatever). Making sure the thumb is halfway between the end and centre. Keeping the other fingers out of the way.
Then you apply pressure with your middle finger, making the same motion you'd make as if clicking your fingers. Open the index finger so as not to get in the way of the pen.
Halfway through the spin, the centre of the pen should go over the thumb. Try not to move the thumb at all. And of course do not let the pen fall, catching it between the index and thumb.
The reverse is possible, just using the index finger to push and middle finger to catch it.
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