Black Market

If you’ve ever pirated music, bought illegal drugs or firearms, or accepted money for a side job without reporting it as taxable income, congratulations--you’ve contributed to the unmeasurable part of GDP known as the “black market.” This allows people to skirt around rules, regulations, and of course, taxes.

Because the black market is--by definition--unregulated by the government (they do try, though), it often ends up being regulated by violence instead. See: The Sopranos.