Back in the lets say from 1880 to the 1950’s it was a tough thing to talk out of the side of your mouth. Many old timers that we knew spoke like that particularly when they were upset or wanted to yell or make a point…for men that is. In New York regardless of ethnic background if you were a tough sort when you yelled it was always out of the side of your mouth.Ever hear a Construction Watchman yelling ”Hey you get out of here” always from the side of his mouth. How this started whose to say .It may have been that way in Philly or Chicago as for that We couldn’t tell you if that was so.
I guess In the movies you always saw James Cagney taking from the side of his mouth when he wanted to act tough.
Even in the movie “‘The Wizard Of Oz “The Lolly Pop Kids ala the munchkins spoke from the side of their mouth as a tough gesture.
AND WHILE YOUR HERE….DON’T FORGET TO VISIT THE ARCHIVES