The Secret Finger Trick (Fingerbootyology)

Step 1. Curl your index finger of either hand into the crotch of your thumb.

Step 2. Rotate your hand so your knuckle is pointing up.

Step 3. Take a close up cutting off the top of the knuckle as shown.

Hint: Some use a photo editing tool for a little blur...
but don't overdo it. Some look best with no blur at all.