My personal experience is that if I'm running my mouth I'm distracted and I might miss something important. So if things are getting weird I usually stop talking and just watch for pre-assault cues.
I never instigate, although I do periodically rant about random stuff to friends while sitting in a coffee shop, and I've had a couple of people take exception to statements like "in general, I'm interested in the decentralization of the monopoly on the legitimate use of violence as an exclusive property of the state".
Also I once sat in a chair and a woman freaked out because she'd put her scarf in that chair to reserve it. The scarf had slid to the floor in between when she put it there and when I arrived at the chair so I didn't notice it. Then, a week later, she confronted me as I was talking about, IIRC, how I tend to view human behaviour through the lens of evolutionary psychology.
She asked if I was evolved to take other people's chairs. I said no, I was evolved to pick scarves up off the floor if I noticed them lying on the ground next to where I was sitting. She said "oh".
Bottom line...Canada is just seething with this level of violent interaction so I try to stay alert.
In all seriousness, when out late and dealing with groups of people around bar closing time, I like to keep moving and keep my mouth shut. We do have a couple of demographics locally that are very enthusiastic about group sucker-punching, and you'll never slip one of those if you're focused on being witty or cutting.
Which they never get anyway, so why bother?