Inefficient Units of Currency

By Joseph Streckert, from the Canadian literary magazine McSweeney's:

• Children
  
• Millstones
  
• Imaginary euros*
  
• Copies of Now That's What I Call Music! Vol. 7**
  
• Pieces of long-grain rice that are not actually very long
  
• Unicorn heads
  
• Canadian dollars

*Arguably, the ECU (which worked perfectly well as a currency) was imaginary.

**Vol. 7 is I suspect now a collector's item. The current volume is 73.