"Number two: don't smack someone in the face. "
You obviously do not have bad eyesight & wear glasses
If you are a glasses wearer and someone smacks you in the face - huge potential of your glasses being damaged meaning unable to see properly and preventing you do ebveryday stuff e.g. being able to drive the car you ahve parked at airport in this scenario. More importantly is risk of lens glass shattering, frame impacting eye etc, etc - basically a whole lot of scenarios with risk of eye damage occuring
So many glasses wearers will retailate (severely and understandably) to a face smack as its a potentially very dangerous scenario for them.