This is a fairly common American-Australian-English vernacular indicating a street punk ("Crusty Punks"). Crusties seem to wear a visibly-recognized similar uniforms of black hooded sweatshirts, skinny black pants and crumbling black Converse sneakers. There are usually a lot of punk-rock patches (homemade, screened canvas patches adhered to jackets, sweatshirts, pullovers, etc. by safety pins) and studded accessories involved. There is a definite semi-anarchist, Food Not Bombs and Homeless Rights ethic to this subculture, at least by the ones I've known in the Bay Area of California.

Crusty. It's not actually an insult, per se, although I guess the use of the word itself is debatably hostile. I've heard more than a couple people refer to themselves as a Crusty, though. Some kids are in bands, some of them are writers, or artists, and I'm sure a few of them are a combination of a few of those occupations. A huge chunk of them can commonly be seen on Telegraph Street in Berkeley, California.

A good read that's in the Crusty vein is the zine "Cometbus," authored by sensitive activist, writer and musician Aaron Cometbus.