Did you wear flip-flops in front of the President of the United States?

The simplest designs are often the most extraordinary, because they solve complex needs with extreme economy of resources. This is the case with the paper clip or the sewing needle. In fashion, a good equivalent is the flip-flop: one of humanity's oldest and most essential designs. Already present in Ancient Egypt—as evidenced by examples found in Tutankhamun's tomb—they were made from plant fibers such as papyrus or palm leaves. Their shape was minimalist: a single toe and a Y-shaped strap between the first and second toes. Nothing more. Similarly, similar variations appeared in ancient Greece, Rome, Mesopotamia, India, China, Japan, and sub-Saharan Africa, made from materials such as leather, wood, or horn. It's surprising how, in such distant places, the same solution was found for a common problem.

Despite the widespread use of sandals in ancient times, they declined in the West, partly due to the emergence of Christianity. Aside from climate issues, the shift from a culture that celebrated the body to one that demonized it also played a role. Leaving the foot partially bare violated the new morality—based on modesty and restraint—and was associated with vanity, lust, and impurity. Consequently, the foot remained hidden until the 20th century, to the point that, during the Napoleonic era, a brief period that revived the fashion of antiquity, optical illusions were used to simulate sandals without revealing women's feet. It wasn't until the 1950s that beach culture and the emergence of surfing revived one of their most historical antecedents: the zori.

Zori are traditional Japanese flip-flops with flat, rectangular soles made of rice straw or wood. They date back to the Heian period (794–1185) and were worn by both men and women in formal attire. Zori became a mass-produced product for everyday wear. In the 1950s and 1960s, Japanese companies began exporting these rubber sandals worldwide, and Western brands discovered the footwear, such as New Zealand's Morris Yock & Son Ltd., "Sandales."

One of the most iconic brands of this type of footwear is undoubtedly Havaianas, which, contrary to popular belief, does not originate in Hawaii, but was founded in 1962 in Brazil, although it adopted that name to imbue them with the summer glamour of these Pacific islands. Havaianas made a rubber version, with its uniquely characteristic rice grain pattern, reminiscent of the zori sandals. A motif on the sole shared with other summer shoes, such as the camping espadrilles that all of Generation X wore during their childhood. Initially, Havaianas were only produced in blue and white, but a production error led to the blue being replaced by green, which gave them the idea of introducing the wide variety of colors that characterize them today. Havaianas have become a basic necessity in Brazil, as evidenced by the fact that the government itself included them on a list of essential products, along with rice and beans.

Although these shoes can now be found in fashion shows, socially they are still perceived as informal. This was demonstrated by the 2005 controversy when the Northwestern University women's lacrosse team (a team sport similar to hockey) was harshly criticized for wearing flip-flops to the White House in the presence of George W. Bush. These shoes reveal as much skin as many sandals, but are still seen as inappropriate today. Further proof that the line between acceptable and indecent can be as thin as a strip of rubber between your toes.