Kid Rock shouted, "Man, f--- Colin Kaepernick!" during a concert at Fenway Park in Boston Sept. 9 (video below).
The crowd responded by cheering the musician, who had a giant American flag on stage, notes USA TODAY.
Besides the F-word, Rock did not elaborate on Kaepernick, who has refused to stand for the national anthem at the beginning of football games because of police brutality and discrimination against black people. Kaepernick's silent and peaceful protest has spread to other NFL teams, as well as high school players.
Rock has flown a Confederate flag, a symbol for black slavery and Jim Crow laws, at his concerts in the past.
In 2015, he issued a statement via Fox News to people who protested his flying the flag: "Please tell the people who are protesting to kiss my ass," noted Entertainment Weekly.
The Intercept reports that the national anthem, "The Star-Spangled Banner," was written by Francis Scott Key in 1814 and includes these lyrics in the third stanza:
No refuge could save the hireling and slave
From the terror of flight or the gloom of the grave,
And the star-spangled banner in triumph doth wave
O’er the land of the free and the home of the brave.
The Intercept notes that Key himself was a slave owner, and wrote his dad in 1813 about how he had just bought "an old woman and a little girl about 12 or 18 years old."
Key offered to send the slaves to his parents as labor for their Maryland plantation, and later asked his mother in another letter how the two slaves had worked out.
Key went from poet to lawyer/lobbyist, and was eventually appointed to be a prosecutor in Washington D.C. by President Andrew Jackson, whom he had gotten to know through political connections.
While prosecuting a doctor who had some anti-slavery literature, Key slammed abolitionists:
[They] declare that every law which sanctions slavery is null and void, and that obedience to it is a sin. That we have no more rights over our slaves than they have over us. Does not this bring the constitution and the laws under which we live into contempt? Is it not a plain invitation to resist them?
WARNING: GRAPHIC LANGUAGE AT :53 MARK
Sources: USA TODAY, Entertainment Weekly, The Intercept / Photo credit: U.S. Navy Petty Officer 1st Class Chad J. McNeeley/Wikimedia Commons