Robert Johnson question?

Stupid question, but this is bugging me.

I recently saw a bio of Robert Johnson where a white guy, also a guitarist, retraced Johnson's steps and interviewed those who knew him.

In the movie they talk about different bars/clubs on street corners and how musicians would play live and attempt to attract the most listeners. (What was this called? It had a particular term...along the lines of 'calling someone out'..etc.)

Also, if you know the name of the bio, that would be great, as I'd like to add it to my collection.

Thanks in advance.