Remoak, if you re-read my various posts you will note that no-where do I endorse shouting. As far as "physical contact without it being in any way offensive" - in today's PC world that would be a very dangerous form of instructional technique.
The Indian guy who used such a technique (the genesis of this thread) was rightly slapped down by the court. He was lucky that my Canadian colleague was not the student or he would have been slapped down all right!