A street person or person of the street. These
people usually dwell in cars that aren't theirs, warehouses, squatting holes, gutters, garbage cans, boxes, parks, opium dens, public bathrooms (bus/train station, airport), bushes, soup kitchen's, etc.
They can often be seen swimming in
yuppie's pools in the daytime while the sell-outs are at
work and carrying a bottle shaped brown paper bag.
Yuppie: get out of my way you
bum!
Urchin: *pulls out urchin/hobo knife* I'm no
bum, i'm an urchin! *stabs yuppie and steal his wallet for booze*
Urchin: *whistles tune* I love to live the urchin life, stabbin
people with my urchin knife