The flags were embroidered with a gold "TRUMP" logo, in a font similar to what is typically used on products and architecture that bear his name.
The flags, paid for by the political activist group Americans Take Action, were handed out to unwitting attendees at CPAC, the largest conservative conference of the year.
From the parking lot to the convention center, the organization's Ryan Clayton and Jason Charter distributed so many flags, they had to return to their car to get more, they said in an interview with Business Insider.
"You can't print TRUMP on an American flag … because that would be disrespectful," Clayton said in an interview with Business Insider. "People were really excited to get red white and blue flags."
After nearly 10 minutes of handing out the flags, CPAC organizers caught on to the ruse, but it was already too late: the president had taken the stage.
"They really didn't notice until a lot of people were waving them [when] the president was speaking. When he finally got on stage, a bunch of people just started waving them," said Charter.
"When the organizers from CPAC came and were tearing them from people's hands, you can see them [upset]," Clayton said of the flag-wavers. "They really wanted their flags."
When asked what message they were trying to send, Clayton said that in "taking the flag and … unwittingly waving it in support of Trump, [that's] the perfect illustration of them … serving Russian interests."
Even after catching on, some attendees weren't entirely upset by Clayton and Charter's antics. "There were a lot of young Republicans who told me that they don't agree with Trump ... so they took the flags."