#Starbucks barista keeps calm during wild rant by anti-masker

A Starbucks barista is going viral for keeping her cool when a California customer went on a wild rant after being asked to wear her mask — even randomly screaming “F–k Black Lives Matter” at the black teen.

Alex Beckom, 19, said she asked the customer to wear a face covering in the java joint in suburban San Diego on Sunday when the woman in a cropped blue top and black shorts started ranting about staff “discriminating against” her.

“F–k Black Lives Matter. I need a straw,” the enraged customer barks at the teen barista. Beckom then politely hands her utensils and some sugar.

In an apologetic tone, Beckom then tells the customer, who had a mask around her chin but not covering her face, that “the next time you come in, I need you to put your mask on” — further enraging the anti-masker.

“No, it’s not a law — it’s not a law! And I can show you the penal code and everything. It’s a hoax!” the customer yells as she starts walking away.

“I don’t have to wear a mask — I’m not going to wear a mask! This is America and I don’t have to do what you say!” the customer screams.

With a loud “F–k you,” the angry anti-masker finally leaves — just to come straight back in for one last shot, again yelling, “F–k Black Lives Matter!”

Another customer immediately sympathizes with Beckom — who was quickly hailed on social media for keeping her cool.

“Mad props to the barista tho. I woulda knocked the lady flat out,” one woman named Gabby wrote on Twitter, while another, named Sara, wrote, “Damn @Starbucks give this woman a raise!!!”

The video also pleased the most important person, Beckom said in a later update — her manager, who was “happy that I managed the situation with poise and maturity,” she said.

“Why didn’t I just punch the lady? Because I like my job, and I want to keep my job,” Beckom said with a smile.

Starbucks told NBC San Diego that the customer’s behavior “is not welcome in our stores.”

“Our focus right now is providing support to our partner who demonstrated tremendous composure during a very difficult interaction,” the coffee giant said.