Trader Joe's employees dress in Hawaiian-themed shirts. Getty Images/Michael Nagel

Trader Joe's employees all dress in a Hawaiian theme for work.

In a podcast where Trader Joe's employees reveal company secrets, Trader Joe's founder Joe Coulombe explains the story behind the Hawaiian shirts with help from Marketing Director Tara Miller and Vice President of Marketing Product Matt Sloan.

One employee said in the podcast that he owns close to 40 Hawaiian shirts.

Trader Joe's employees are known for always dressing in a Hawaiian theme.

But it isn't without reason. When Joe Coulombe founded Trader Joe's stores in 1967, he carefully picked its nautical theme.

"I'd been reading a book called 'White Shadows in the South Seas,' and I'd been to the Disneyland jungle trip, and it all coalesced," Coulombe explained in the Trader Joe's podcast where execs reveal company secrets.

"White Shadows in the South Seas," the book by Frederick O'Brien that Coulombe was inspired by, takes place on an island in the South Pacific.

And to this day, Trader Joe's employees — whom the company calls "crew members" — all wear Hawaiian shirts because of that.

"We wear Hawaiian shirts because we're traders on the culinary seas, searching the world over for cool items to bring home to our customers," Trader Joe's writes on its website.

"And when we return home, we think grocery shopping should be fun, not another chore. So just relax and leave your worries at the door. We'll sail those seven seas, you have some fun with our finds at your neighborhood Trader Joe's."

Trader Joe's CEO Dan Bane said he owns more Hawaiian shirts than he can count, but donates a lot of them to charity each year. Other Trader Joe's employees have said they have entire closets filled with Hawaiian shirts, with one employee saying in the podcast that he owns close to 40.

The Trader Joe's podcast is hosted by Vice President of Marketing Product Matt Sloan and Trader Joe's Marketing Director Tara Miller. It covers topics like the retailer's products and values, the history of the chain, why it calls its employees "crew members," and its famously cheap wines.