Special purpose money
"Objects that serve as a medium of exchange in only limited contexts. In societies that have it, usually there are certain goods and services that can be purchased only with their specific form of special purpose money. If you don't have it, you cannot acquire the things that it can purchase. You may not be able to easily obtain the special purpose money either. The Tiv people of central Nigeria provide an example. In the past, they used brass rods to buy cattle and to pay bride price. These rods were acquired by trade from Sahara Desert trading peoples who ultimately obtained them from the urbanized societies of North Africa. If a man could not acquire brass rods by trade or borrowing them, he would be prevented from acquiring cattle and getting married. See general purpose money". http://anthro.palomar.edu/tutorials/cglossary.htm
(facebook money, club penguin money -- different items have different values in different contexts online -- people have certain values in some contexts).