I have witnessed full maan-behen and WWF tag team type wrestling on a Tokyo-Islamabad flight, not to mention the minor entertaining incidents over the years (and this, despite the fact that PIA is always my last option).
A group of guys who had brought their own maikhaana (liquor, trays, and all) were enjoying a very wet conference (two seated, another two standing), and were quite drunk very early in the flight. Then the inevitable maan-behen started. A few people complained, only to trigger more maan-behen.
Then an elderly gentleman stood up and announced in no uncertain terms that if the conference was not terminated immediately, he will have to take the law into his own hands. He rightly pointed out that people's maan-behens were on the plane, and so there was no need for maan-behen. One of the conference guys (bearded cheerleader) ridiculed him apparently because of his age, and went close to the old man. It was a mistake because the old man was sober and the cheerleader was not. Before anybody knew punches were being thrown from both sides. The old uncle was landing 9 out of 10 punches while the cheerleader was hitting some imaginary person a few inches to the left of the old man.
The other people from the conference ran to help their comrade but the old man's courage had motivated quite a number of people by this time and they were intercepted and thrown back into their seats humiliated. The cheerleader, who now had no face to show to anybody, went to his bag, pulled out something black from it and shot the old man. It was apparently a camera and he announced that he will get the old man arrested the moment we landed in Islamabad (that turned out to be an empty boast because the cheerleader was among the first people to be seen leaving the airport).
Two things stood out in that whole affair:
1. The cheerleader's ten-eleven years old son was very calm throughout the whole time (including when his old man was being pummeled), peacefully eating his "chips". I thought he was either a kid with superhuman qualities or he was used to such scenes.
2. The PIA staff did absolutely nothing to prevent or stop the fight. Once the public took care of the scoundrels, they came in and made all the right noises of course, but they stayed clear before that.