My cousin tended bar at Mo's out in Katy for 20-odd years. The bouncer he most respected was a Marine who wasn't large, or tall, but had presence. He said the bouncer instructed him, "Never hit them in the head. Too much bone. You'll break things in your hand."
One evening, a large fellow was all worked up with some other large fellow, and the bouncer moved in to break it up. The larger of the two guys swung at him, and the bouncer ducked it and grabbed the large fellow by the fleshy part of the pectoral muscle where it goes over the armpit and pinched. Hard. My cousin tells that the large fellow immediately quit struggling, and said nothing but whimpers and weak, "Yes, sir!"
"He had a look on his face like he was amazed that something could hurt so much!"