Where are they from? If they are not from the US that term doesn't apply to them.
Karen is just the latest term used by African Americans to refer to a meddlesome white woman from the US who uses her white privilege, sometimes to deadly consequences. US history is littered with white women terrorizing non white people by accusing them of something, which is followed by the white man then taking action. Emmett Till is probably the most famous example;
https://en.wikipedia.org/wiki/Emmett_Till
"Emmett Till was an African American boy who was abducted, tortured, and lynched in Mississippi 1955 at the age of 14, after being accused of offending a white woman, Carolyn Bryant, in her family's grocery store."
Good article in the New York Times on this; How White Women Use Themselves as Instruments of Terror;
https://www.nytimes.com/2020/05/27/opinion/racism-white-women.html
"We often like to make white supremacy a testosterone-fueled masculine expression, but it is just as likely to wear heels as a hood. Indeed, untold numbers of lynchings were executed because white women had claimed that a black man raped, assaulted, talked to or glanced at them. The Tulsa race massacre, the destruction of Black Wall Street, was spurred by an incident between a white female elevator operator and a black man. As the Oklahoma Historical Society points out, the most common explanation is that he stepped on her toe. As many as 300 people were killed because of it. The torture and murder of 14-year-old Emmett Till in 1955, a lynching actually, occurred because a white woman said that he "grabbed her and was menacing and sexually crude toward her". This practice, this exercise in racial extremism has been dragged into the modern era through the weaponizing of 9-1-1, often by white women, to invoke the power and force of the police who they are fully aware are hostile to black men. This was again evident when a white woman in New York's Central Park told a black man, a bird-watcher, that she was going to call the police and tell them that he was threatening her life."
Look at the reaction to the 1915 film The Birth of a Nation
https://en.wikipedia.org/wiki/The_Birth_of_a_Nation#Audience_reaction
Your friends need to stop attaching a label that doesn't belong to them, nor feeling annoyed over their ignorance, and also educate themselves on the misery and terror inflicted on a group of people.