I had an interesting experience some years back. I had been teaching a corporate English class for Nanshan Insurance for some time, and we decided to take a class trip to Kending for the weekend. Well, on the way back, we stopped in Pingdong County in a little village (I think it was called Wanru) to get some pig knuckle, a local specialty. Well as we approached (on foot) the small lane where this commodity could be had, we saw there was quite a commotion. It turns out an elderly man (not a day under 75) and his wife had parked their car momentarily in the middle of the narrow lane while they ducked inside to buy something. Not exactly stellar road etiquette, but still nothing deserving of the beating the old dude was getting from some 30-something hotshot in a Honda Civic who was unable to get by the old dude’s car.
There were maybe 50 people watching, including able-bodied men. I, too was rubber-necking, until I realized what was going on, and the old dude’s wife was crying, trying to pull her husband away from the attacker. At this point I said “fuck it” to myslef and stepped in. (At the time, I was 27 or so, in good shape, a 2nd degree black belt in TKD, 6 ft. tall, 185 lbs, and most importantly I had 2 years not-too-distant experience working as a bouncer in a fairly rough nightclub in my hometown while I was in university. Not exactly Steven Seagal, but not exactly Peewee Herman, either. 
)
I got in between them and told the young guy (in Mandarin), “hey, let the old guy go, it’s no big deal, he’s old, come on, forget about it.” He put his arms down, utterly confused, and I dropped my arms (outstretched to put some distance between the two) down also. He recovered to immediately shoot a fist past me connecting with old dude’s face, knocking off his glasses, and possibly breaking his nose. (There was lots of blood, and I could hear a crunch.) I pushed the guy’s arms down and he shoved me in the chest hard. I then shoved him back ten times as hard and sent him skidding on his ass. He turned beet red, mad as fucking hell, 
and came charging at me. I stepped forward and brought a forearm under his chin and slammed him down on his back on the hood of his civic (I dented it, I think) I then hissed at him, “You don’t hit women, you don’t hit children, you don’t hit babies, you don’t hit old people. Got it?” I relaxed my arm enough to let him breathe a bit, and he didn’t say anything so I leaned down on his windpipe a bit more and repeated myself. Once he finally muttered the words I wanted to hear, I got off him, he got up and ran to his car.
I was quietly praying that he didn’t have a gun in there, cause if he did, he would have surely killed me, he was that mad. 
He took off like a bat out of hell, tires screeching madly. In the meantime, the old couple had beaten a hasty retreat. I can’t say as I blame them, as the old dude’s nose was a bit of a mess, and they were very frightened.
After that, the boss of the pig knuckle shop presented me with a bag of that incredibly greasy-but-delicious meat. And my students decided we should beat it before the guy came back with every xiongdi (gangster) in the county. They were pretty shocked. 
I was pretty upset.
“Listen”, I said. “Right now that guy hates foreigners because I schooled him in front of dozens of people. He still has no idea that what he did was unacceptable behaviour in the eyes of society, because noone in his society did anything to indicate otherwise. There are 8 able-bodied men in this group. Why weren’t you guys in there? What were you thinking?”
They said that it was impossible to tell who was at fault.
I was having none of that. “The old guy was at least 75 years old, right? He was getting beaten up for bad parking, right? The attacker was a young guy, right? What else is there to know?” 
They said I did the right thing, but they were worried that maybe the guy would turn on them. I let it go, because they were embarrassed. 
The funny thing is, we never talked about it, but at least half of the class sent me private e-mails later thanking me for what I did. Publically, the whole event was viewed as something that somehow shouldn’t be talked about. Weird. Good one for the memoirs, though. 