The replacement name for the currency of a foreign country which you are visiting, but don't know the actual name of.
Especially used for poorer Eastern European or third world countries, in which your home currency has a better exchange rate.
At the airport:- "I'm off to exchange my dollars for some durka durkas."
At the market:- "This knock off Armani bag only cost me 3 durka durkas!"
At a restaurant:- "Jellied camel toes for half a durka durka! We can eat like kings on this exchange rate!"