The secret to being cool in Rio is to wear these on your feet

Havaianas - flip-flops made in Brazil

As Olympic athletes change out of their athletic sneakers, chances are they are putting on a pair of Havaianas. They are the must-have sandal of Brazil, and the world for that matter.

"Brazilians don't say they are wearing flip-flops — they say they are wearing Havaianas," said Inhwa Lee, Havaianas' director of marketing for North America.

The brand, established in Brazil in 1962, has grown into a global footwear powerhouse even despite a recession plaguing its native country. "We sell about 220 million pairs per year," said Lee. "That means we produce about eight pairs per second in our factories."

Brazilian flip flop company Havaianas introduces a pair to commemorate the 2016 Olympics in Rio.
Source: Havaianas

That's a lot of flip-flops. The company says since its inception, it has sold about 3.5 billion pairs in total. That's enough flip-flops to circle the Earth about 47 times.

The simple rubber shoe comes in nearly every color of the rainbow and typically sells for anywhere between $20 and $40.

Havaianas may be known for its flip-flops but the brand has expanded to sandals and even shoes. However, it still tries to stay authentic to the brand — a pair of espadrilles has the rubber flip-flop sole with a canvas top.

The brand's success has attracted big-name partnerships and licensing deals — from Missoni to Valentino. And corporate partners like Disney.

"We are the exclusive and official flip-flop of Walt Disney World resorts," said Lee.

Havaianas store flip flops
Justin Solomon | CNBC

Currently, you can find this flip-flop favorite in the 500-plus Havaianas stores and authorized sellers around the world. They have nine retail locations in the United States, a number it expects to grow rapidly.

And in Rio de Janerio, at the Olympics Megastore — Havaianas branded with Olympic rings are flying off the shelves. With crowds often pushing their way into a pack of customers to find their sizes, all while workers try to replenish supply.

"We have been able to create a lot of brand buzz and make people aware that we are not just a flip-flop," said Lee. "We are a must-have item."

Disclosure: CNBC parent NBCUniversal owns NBC Sports and NBC Olympics. NBC Olympics is the U.S. broadcast rights holder to all Summer and Winter Games through the year 2032.