Two protesters have thrown milkshake at UKIP European election candidate Carl Benjamin at a rally.
Mr Benjamin was holding a gathering on Lemon Quay in Truro, Cornwall, with British activist Milo Yiannopoulos.
It is understood a man and a woman tried to target Mr Benjamin with the milkshake but missed.
Supporters of Mr Benjamin pulled the man to the ground after he threw the milkshake. Police said they received reports of an altercation.
The man was later seen walking away.
A Devon and Cornwall Police spokesperson said: "A milkshake was reportedly thrown over a member of the public by a man wearing black clothing and a white mask.
"Police carried out inquiries but the 'victim' did not make themselves known to officers.
"No official complaint has been received."
A female protester was also prevented from throwing kippers at Mr Benjamin.
At the scene
By Johnny O'Shea, BBC News
One of the protestors across the square was performing with a jazz trumpet to drown out Mr Benjamin when a man with a scarf partially covering his face and a hooded woman pushed their way through the crowd holding bottles of milkshake.
The pair missed their target, with the milkshake instead going on to other people and over the floor.
They were pulled away by a number of Mr Benjamin's supporters and a scuffle started with punches and kicks being thrown.
Mr Benjamin began his speech by saying: "Thank you to the protestors who have assaulted me already."
Other protesters at the rally included a busker who set up close by, playing loudly to try to drown the two speakers out.
Police are currently investigating remarks made by Mr Benjamin after Labour MP Jess Phillips accused him of malicious communications.
Mr Benjamin is running to become an MEP for South-West England, one of 47 candidates in the constitiuency.
The Truro incident comes after Tommy Robinson, whose real name is Stephen Yaxley-Lennon, had milkshakes thrown at him in Warrington, Cheshire, and Bury in Greater Manchester while campaigning as a European Parliament candidate for North-West England.
Who are Carl Benjamin and Milo Yiannopoulos?
YouTuber Carl Benjamin, known online as Sargon of Akkad, was unveiled as a UKIP election candidate last month.
He sparked outrage when tweeted in 2016 that he "wouldn't even rape" Labour MP Jess Phillips.
He has refused to apologise for the remark, arguing that "any subject can be the subject of a joke."
Last month, members of UKIP's Swindon branch said Mr Benjamin had only joined the local party recently and he should be deselected.
Milo Yiannopoulos is a British writer and editor, based in the US.
He has been widely criticised for comments he has made about transgender people, Muslims, Black Lives Matter activism, feminists and gay people, even though he is openly gay.
In July 2016, Mr Yiannopoulos was banned from Twitter for what the social media company referred to as "inciting or engaging in the targeted abuse or harassment of others".
He was also banned from Facebook earlier this month.