I would point to the Japanese footwear called zori as the source of today’s flip flop. In the 1930s, straw zori originating from Japan first appeared in New Zealand, Australia, and America as beachwear. But it was after World War II that many American soldiers brought back the zori after their tour of duty in Occupied Japan or when returning from duty in South Korea after a last stop in Japan on their way to the United States. So it was in the late 1950s, when the zori began to hit the stores as great, cheap summer wear, particularly for kids. I had a pair in yellow and white that I wore constantly, and I remember having to pop the portion that divided the toes back into the thick rubbery soul. My dad, who had served in the U.S. military in both Occupied Japan and in South Korea, called them zori(s), and the name stuck for me