I encountered a group of these on my very first trip to Baltimore back in 2002. I was stopped at a stop light in a bad neighborhood and I saw the swarm coming in my rear view mirror weaving in and out of traffic. They were also riding on the sidewalks and some were riding up the townhouse porches and jumping back down.
I had a front row seat as they entered the intersection, stopped cross traffic, and began circling as a large group right in the middle. After the lights cycled through a phase, they rode off in another direction.
It was on this same trip that I was exploring DC when an elderly black man approached my car at a stop light and kindly informed me to immediately turn my car around and drive right back where I came from. He wished me no ill will but guaranteed me, being white, or my car would not make it unharmed if I continued in the same direction I was going.
Boom lacka laka, cracka. You know your place.....