I know exactly what you mean and it is definitely harmful to discussion.
I don’t know if it needs a whole flag type, but here’s what I recommend:
- flag it for mod attention with a note
- the mod (ideally) comes in and posts a reply asking the two people to cool it
However that doesn’t help you if no mods are around. I might even suggest posting as yourself (non mod, just another user) and asking the two people to cool it.
Maybe related story.
One night in Boulder, Colorado as I was driving home late from my job – this was maybe around 1992 or 1993 – I pulled up at a traffic light in front of two other cars. Not many cars were around, it was dusk, maybe 7pm or so at a relatively deserted intersection on the outskirts of town.
Anyway, these two guys were yelling at each other for some reason. Then they both got out of their cars, I swear to God, and were about to have an actual throwdown fisticuffs fight in the street. At this point I’m pissed because I’m sitting behind them at this traffic light and I can’t go anywhere with these two jackasses out of their cars.
So I lean out of my car window and yell as loud as I can, GET BACK IN YOUR CARS!
The two guys look at each other sheepishly, get back in their cars, and drive away.
True story. I’ve always remembered that.