Want to know why US currency, after being so stable in appearance, has changed so frequently of late? How about this:

Millions of dollars of the fake cash have been passed into circulation since [the superdollar's] existence was first noticed over a decade ago.

The money, officially known as Note Family - C14342, is thought to originate from communist North Korea.

Guess it's a good thing North Korea sits on some of the most worthless real-estate on the planet. Imagine what they'd be like if they had natural resources.