One of Trump's supporters reportedly faced backlash while appearing amid a protest against the president in London on Tuesday.

A video, posted by LBC reporter Matthew Thompson, showed the man surrounded by several people who yelled "Nazi scum" at him. It's unclear what the man said in response but at one point, a milkshake fell on his head -- leaving residue at the top of his face.

As the crowd cheered, he threw the milkshake back and seemed to try and attack one of the crowd members before people pushed him back.

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The incident occurred as London erupted with anti-Trump protests amid his visit to the United Kingdom on Tuesday.

Police also reportedly barricaded about 20 Trump supporters in a pub amid the protests. Among the protesters was a blimp of Trump as a baby and women dressed as "handmaids" from the popular series, "The Handmaid's Tale."

Trump himself faced resistance when London's mayor Sadiq Khan penned an op-ed complaining that it was "un-British" for the nation to roll out the "red carpet" for Trump.

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"Donald Trump is just one of the most egregious examples of a growing global threat," he said. "The far right is on the rise around the world, threatening our hard-won rights and freedoms and the values that have defined our liberal, democratic societies for more than seventy years."

On Twitter, Trump blasted Khan as a "stone cold loser" who reminded him of "very dumb and incompetent" New York City Mayor Bill de Blasio.

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"Kahn reminds me very much of our very dumb and incompetent Mayor of NYC, de Blasio, who has also done a terrible job - only half his height," he tweeted.