I'm gonna just guess that a "Bang Back" is where you slap the side of the machine? Right?
OK, if so here's a story. It will might piss someone here off but Oh Well.
I was in the Tournaments at PATZ on Saturday. There was this young kid, probably 14 or 15 yrs old. He was using this technique on the machines. I understood the jist of what he was doing although I must admit until I read this thread I didn't know that it was a common thing or technique. I've always just been a semi-nudger myself.
Anyways, like I said he was just smacking the shit out of these really nice machines AC/DC, Tron and Avatar. Not that the Classics in the line up deserved to be smacked either, but you know what I mean. These were obviously not his machines to be doing what I considered abuse to..
Plus he had just horrible sportsmanship, he was getting all pouty and I remember seeing him purposely Tilt a few times.
All the time I'm thinking this kid needs some counselling or something? JMHO though maybe I'm getting old?
Oh yea another thing, he kept trying to take my stool that I brought from home. I need a hip replacement and brought because I can't stand long periods at a time.. If I turned my back to sign up for a game or something, I'd turn back around and he was trying to pull it away to sit on. He did this shit twice.. I'm thinking Jesus kid, I can barely walk and you're gonna take my stool every time I don't have my hand holding it down?

Just Bitchin I guess, but glad those weren't my machines there. I would more than likely said something.. Maybe I'm just a dick IDK?

Bill in Indiana