A very obviously depressed and isolated person stuck in big cities like Chicago or NewYork. They walk up and down streets and alleys usually in the rain, cold, or early morning since the streets are less populated. They wander busy streets and alleys often tilting their face toward the sidewalk to avoid possible eye contact with others and usually use alleys to avoid people all together. They "worm" or "snake" their way through the city and can usually be identified by the cold depressed look on their face as they quickly move in contemplation.
Street worms aren't just homeless people or depressed hipsters. They can be people of all walks of life who just are clearly in some kind of depressed state and are trying to avoid people even though its almost impossible in major urban areas.

"These art school alley ways are usually flooded with street worms especially when it's raining"
by FutureGhost November 13, 2018
Get the Street Worm mug.