Answer this for me.
A door-to-door salesman (think Avon, vacuum cleaners, etc) comes to your home and says;
"I have a great new product I reckon you'd be interested in. It's a crypto-currency called Bitcoin.
It's like a normal coin except it's digital and is mined by super computers which generate a Bitcoin every time they solve a very complex puzzle, reports News.com.au.
We don't know who the miners are but these Bitcoins were originally used by drug cartels and arms dealers to launder their money and trade between each other to avoid the authorities.