Police were called to investigate a complaint about a European flag flying in Rory McIlroy's home town in County Down during the Ryder Cup.
It was flown at a house in Holywood where a Ryder Cup party was held.
The owner of the house was stunned when two police officers arrived at his door on Sunday morning.
In a post on Facebook, he said that the person who complained thought it was an Arabic flag.
He said: "Right in shock here. Had a Ryder Cup party yesterday and just had the police round ... as apparently it's caused offence."
In a statement, the PSNI confirmed its officers became involved.
A spokesperson said: "Police in Holywood attended an address in the Woodlands area yesterday following the report from a member of the public that a flag they believed to be offensive had been erected.
"Police attended and no offence was detected."
The flag was put up on Saturday, the second day of the Ryder Cup which Europe went on to win with the help of Holywood hero Rory McIlroy.
The flag-waving golf fan, who did not wish to be named, said: "I was having a house-warming party and decided to put up the European flag for the Ryder Cup.
"I was tidying up on Sunday morning and two police officers arrived. They didn't seem to know what the flag was themselves.
"I said 'it is a European Union flag for the Ryder Cup'.
"They said there'd been a complaint about it being some sort of Arabic flag.
"I just laughed. In the end they were laughing too. It was crazy."
Local Alliance Party councillor Andrew Muir said: "In some ways you couldn't make it up.
"It's rather depressing that we would be focused upon flags. People are entitled to fly whatever legal flag they want from their house and in Northern Ireland we need to be able to celebrate our success and the European flag is an open, inclusive symbol of Europe coming together."