After WWII soldiers brought back Japanese footwear called Zōri, the design is more of a rectangular shape, as opposed to the foot shape modern flip flops have adopted. Made from rice straw or lacquered wood, they are easy to slip on and off like most Japanese sandals, because when entering a house footwear must be removed.
English speakers dubbed these no heel strap sandals with the term "flip flop" which is the sound they make when you walk. While this is the most common name used they do go by others, such as: thongs or pluggers in Australia, or jandals in New Zealand (short for Japanese sandals) and slops in South Africa and Zimbabwe.
The flip flop is one of the few items that use an onomatopoeia as a name.
By James Moore, your friendly neighborhood flip flop lover.