The infuriating reason a waiter refused to serve four women.

A waiter at a Southern Californian restaurant has been fired, after he asked four female customers to “prove their residency” before he would serve them.

Diana Carrillo posted about her experience at Saint Marc Pub-Cafe, in Huntington Beach, on Facebook on March 11.

Her post has now been shared over 1,700 times.

“My sister and my friend were seated first and the waiter asked them for their ‘proof of residency’ when they ordered a drink,” she wrote.

"My friend in disbelief repeated what he said and his response was, 'Yeah, I need to make sure you're from here before I serve you' (sic)."

Diana said the question was repeated when she and her friend were seated.

"After fully digesting what he said, we all got up and left to speak to the manager. For a few seconds I thought maybe he was being a smart ass or joking but the fact that he said "I need to make sure you're from here before I serve you" was completely unacceptable," she wrote,

"How many others has he said this too? I hope this employee is reprimanded for his actions. No establishment should tolerate discriminatory actions from their employees."

Speaking to BBC News, Diana - who has Mexican ancestry but was born in the US - said she has "never faced discrimination like this in the past."

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She believes the election of Donald Trump as President has made people less afraid to "openly discriminate" against others.

"I think a lot of people think they have the power to discriminate against people more openly than before," she said.

She also said that while many believed her story was "fake news", the shocking incident did indeed take place.

"Unfortunately it did happen and it happened to me and three other people. We have to bring awareness to racism and address this," she said.

The senior director of operations at the restaurant, Kent Bearden, confirmed to the Washington Post the waiter at the centre of the incident had been fired.

"That individual did not treat a table of guests to the expectations that we set forth in that company policy, and that caused him to be terminated," he said.

An offical apology was also posted on the restaurant's Facebook page, but has since been deleted.