A woman is buying many coconuts for 5\$ a dozen. Afterwards, she is selling the coconuts for 3\$ a dozen.
After this transaction, the woman has become a millionaire!
How could that happen?
This is a lateral thinking riddle :-) Try to become aware of your silent assumptions. List all the aspects you are assuming, and question them.
Source: I found this riddle on the webpage of Jürgen Stock.
However I think this riddle is widely known in the Lateral Thinking community. I share it because it hit me where I found it amazingly difficult to become aware.