When I was walking around Manhattan, I was noticing that people talk fairly loud, to be heard over the din of traffic, subway trains, etc. So when you went by someone walking and talking you get a 2 second excerpt of their conversation. My favorite was "and then I got to meet Cyndi Lauper."
This is a site dedicated to things you overhear on the street in NYC. Of course editing and embellishment can happen since this isn't peer-reviewed, but the best of them have the ring of truth. EG
More Like Man-dog
Teen #1: Damn, kid! Your face mad hairy!
Teen #2: I'm a grown-ass man, dog.