When someone flexes like that and utters "i will knock you the fuck out" watch out for a sucker punch. most guys who says that will do it when you're not alert. Witnessed one guy went on someones face at a bar in richmond hill once...said exactly the same..."say one more word and i will knock you the fuck out." We were not involved but my friend who is a boxing trainer told the guy...if they want to fight...his gym was across the street and he can lace them up and see what they got....the tension decreased significantly...LoL.
From my own experience, only pussies utter threats, either verbally or by pointing a weapon that they have no intention of using. The same applies to people who threaten to call the cops. They are weak, but at the same time they try to be intimidating, because they assume that other people are as weak as they are.
In my neighbourhood, I see a lot of 'passive-aggressive' fights, where two people diss each other from a safe distance, trying to provoke the other to throw the first punch. Generally the spectators are silently laughing at both of them.
I did see a decent parking lot fight recently, between two Black men in their twenties. The smaller guy was trolling a very large dude, who clocked him with one punch, then walked away. I gave the big guy a bottle of cold water, (I'd never met him before), as he was walking away, because he had exercised sufficient restraint, and I wanted to help him 'cool down' so he didn't do something stupid while he was pumped with adrenaline. The two guys walking with him said 'bro, take the water', and he did.