A Starbucks barista reveals the number one most annoying drink customers can order

A Starbucks barista recently revealed what is unanimously the most annoying drink that customers can order at the international coffee establishment.

If you're a fan of Starbucks, you might be familiar with some of their more complicated menu items that span beyond your usual cup of drip or iced coffee. You have your usual suspects (latte, cappuccino, americano) - but then, on a separate level, you have your cold brews with cold foam, your frappuccinos, and a slew of other fairly complicated drinks.

If you've ever wondered which drinks are the most annoying and hardest for Starbucks baristas to make, look no further - we got the word straight from the source, and the answer in regard to the number one most annoying drink a customer can order may surprise you.

Monica MacDonald, who worked as a barista at Starbucks for over two years, told Insider that when she worked there, she could remember a few drinks that made her and the other baristas give a little eye roll when they received the order.

First and foremost, she said, were the S'mores Frappuccinos, as they were "inconvenient."

"The Frappuccino starts with marshmallow-infused whipped cream, which is specially made. This means that if you've run out, you have to prepare a new canister of it before you even start making the Frap," Monica said. "After that's prepared, the drink is made with layers of chocolate sauce and vanilla-flavored Frappuccino, then topped with the special whipped cream and graham-cracker dust."

So, while it is delicious, it's really time-consuming - and therefore, quite irritating to make, according to Monica.

Monica also noted that it can be difficult and ineffective to order a cappuccino with non-dairy milk, as nut milks, coconut milk, and soy milk don't froth the way that dairy milk does.

"The proteins in non-dairy milk are not as strong as they are in cow's milk and thus it can't keep air bubbles quite as well," she said. "So when you try to froth a non-dairy milk, like coconut milk, the results aren't exactly the same — you get some airy sort of foam, but mostly just steamed liquid."

She also mentioned that sometimes an iced matcha latte can be a nuisance to make, especially if you ask for no ice.

"To make an iced green tea latte, the matcha is added to a cup with ice and milk and then physically shaken. This can be an imperfect method that sometimes results in a clumpy drink," she said. Plus, when you ask for no ice in this specific drink, there's "practically no way to make sure the drink is homogeneous and it often results in a clumpy matcha latte."