The Onion can be brilliant, and this piece from February proves it. Yes, money is just made up. Now what? Same as always: making up social institutions is just what humans do.
The funny thing is that a part of my dissertation research is on the human ability to create social institutions that seem just as real as the rest of reality. Money is one such institution. What makes us human is that we can produce these things at will – and also, when necessary, will to change them.