A New York artist is challenging our assumptions about money and currencies. When Nicky Enright hawks his “international currency,” the elaborately designed “Globo,” in a “buy-one-get-one-free” deal that’s offered for “a limited time only,” the people he meets are both confused and intrigued. What is it? Is it worth anything? What can they buy with it? And the big question that gnaws at them: Is it “real?”