Knives, Knives Everywhere

I was on my way to work this morning and while traveling down Columbia Road… in the Dorchester neighborhood of Boston… I came to a stop behind a vehicle at a traffic signal in Fields Corner.
 
While waiting for the traffic signal to turn green, I noticed a man come over to the passenger side window of the vehicle in front of me. The man pulled a knife… it looked like a steak knife… out of his pants pocket and started waving it. I couldn’t make out what he was saying because my windows were rolled up and my radio was on.

After the man was done gesticulating, he turned around, put the knife in his left pants pocket and walked away. At that point, the traffic signal turned green. I didn’t know whether the man was returning to a parked vehicle or getting back onto the sidewalk.

What’s the point of the story? Assume everybody carries a knife!