And I must add one more thing, I got interested and read more comments on that subject: the one I would agree with is hitting man in left back side of neck. Tried it on myself - it is only one point where I feel slight tingling in neck when I hit it and my left arm is tingling for a little moment, just like after hitting something hard with elbow. It is unpleasant sensation and if I hit powerful enough I think I would be dizzy and possible pass out. The spot is about 2 cm up from a bone, behind a string of muscles which goes after left ear.