The proper way of cold cocking the unsuspecting victim is from the side or rear. There is no facing off or shoving, etc. No warnings at all. Originally referred to before political correctness as "japing" some one.
It became a common tactic after the Vietnam war on the inner city streets. First learned in the prisons when shanking another inmate, black gang bangers picked up on it. No longer a facing down then escalating to a shoving match before the fist and feet go flying. Now it's one punch with no warning to take the victim down. One punch, one knock down. A few good kicks to the ribs and head for the coup de grace.