[UPDATE]: May 25 — After some initial confusion on Twitter, with readers in Chicago demanding to know what exactly a “Chicago Bun” was, some clarification was reached. Apparently many of them had never heard of a "Chicago Style" burger or bun.

@me3dia @jennypfafflin Here - @EvanLancaster85 wrote it. Let's ask him. What the hell is a Chicago style bun? Sincerely, Chicago.

— John Carruthers (@UTChicago) May 23, 2017

@EvanLancaster85 what is a Chicago style burger? I have lived in Chicago all my life. Never heard of a Chicago burger.Please explain.

— richard emperado (@richardemperado) May 23, 2017

Fortunately, Costco management responded, clarifying the reasoning behind the “Chicago” naming confusion.

“The vendor calls the hamburger bun out as a “Chicago Bun” on a sticker which is affixed to the outside of the box it’s delivered in,” a Costco representative said on behalf of Costco management in an email. Adding, “We make no reference to that term ("Chicago Style") in our item description or step by step formula.”

To be more specific, Costco management clarified that the bun is actually a challah bun, a roll made with Jewish bread dough.

Costco Food Court lovers have a reason to celebrate, as it looks like the menu is expanding. Currently, Costco Wholesale locations in Corona, Pacoima, and Lakewood, Calif., with other out of state locations in Seattle, Wash., are testing a 1/3 Lbs. Chicago-Style cheeseburger, and like everything else at Costco, it's massive.

It's an organic beef patty, topped with romaine lettuce, smoked Thousand Island dressing, tomatoes, and cheddar cheese, all placed between fluffy, sweet Chicago-style buns. In true Costco fashion, the new burger is an affordable $5.43 with tax, which means you can still grab a delicious slice of pizza or a Costco hot dog without breaking the bank.

However, while this might seem like a new addition, Costco has experimented with cheeseburgers before. About a year ago, Reddit user Forrest263, posted a photo of a Costco Food Court menu, featuring a 1/3 Lb. cheeseburger in Livermore, Calif., but by the looks of the photo it was served on a ciabatta roll, not the current Chicago-Style bun.

While visiting the Long Beach, California location, a Costco employee relayed that Costco would be rolling out the new Chicago-Style Cheeseburger in additional locations by March 2018.

In that case, we're marking our calendars.