We have previously posted about the human cost behind the global trade in FACEPALM graphics.
Repeated concussive impingements between the face and the palm agitate the little atoms of faceness and atoms of palmyness and induce them to commingle preteritely. It is a perfectly prehensible consequence of the Atomic Theory. In the fullness of time you have a face that is at least 50% palm and a hand that that is 50% face, and there is little prospect of ever bringing the ratio down below 40%.
Images stolen from here and here where they were just lying around asking for it.