Words for the Wanton.

An American friend recently used the word ‘slag’ in connection with a mutual acquaintance, and I’m curious to know its origin. I’m sure we must have it over here because it wasn’t entirely unfamiliar, but I wouldn’t say it’s our first choice. We tend to prefer the old fashioned ‘tart’ or the more modern ‘scrubber.’ I don’t know where they come from either.

I’m also curious to know what they’re called in other English-speaking parts of the world, especially those in which the concept itself is relatively rare.