I noticed it in the Pratie Heads’ cover of the traditional tune, “Knickerbocker Line,” and thought I might use it in a book. But when Emma and Lorraine were talking about possible band names in an Irish bar in St. Paul, I heard the phrase again: Martz and Menton were singing another traditional song, “House-husband’s Lament (Rocking the Cradle)”, and when they got to the line, “Come all you young men with a notion to marry/Oh, pray, won’t you leave those flash girls alone,” I realized Emma and Lorraine needed the phrase more than I did. And they agreed.
“Flash” is an old bit of British slang. According to the 1811 Dictionary of the Vulgar Tongue, a Dictionary of Buckish Slang, University Wit, and Pickpocket Eloquence, it means “knowing” or “ostentatious.” In context, it suggests one knows a little more than is socially appropriate, and one has a tendency to dress and behave in ways that suggest that’s so. In other words, a flash girl is one who is no better than she should be.