Warning: This video and story contain strong language.

Kid Rock was not shy in expressing his feelings about NFL player Colin Kaepernick during a recent concert at Fenway Park in Boston.

The San Francisco 49ers quarterback has recently adopted the habit of sitting during the National Anthem at games, instead of standing up with his hand on his heart as is customary. When a film of that went viral, he explained his actions in an interview with NFL.com, saying it's a deliberate social protest against police violence.

"I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color. To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder," Kaepernick said.

Kid Rock is a staunch social conservative, and when he shared the stage with Jason Aldean for a two-night stand at the stadium venue on Friday night (Sept. 9), he took a moment during his show, in the middle of his hit song, "Born Free," to express his disdain for Kaepernick in no uncertain terms.

In the video above, the flamboyant entertainer is performing in front of a screen depicting a giant American flag. Toward the end of the song, he brings the music down, kneels in the spotlight at the front of the stage dramatically, then raises up and shouts, "Man, f--k Colin Kaepernick!" before resuming his performance, to the cheers of the assembled crowd.

USA Today reports Kaepernick continued his protest on Monday when the NFL kicked off their season against the Rams, and he was joined by his teammate Eric Reid, as well as Rams players Kenny Britt and Robert Quinn, who raised their fists.

Fortunately for Kaepernick, the NFL has taken a cooler approach to his actions.

"The National Anthem is and always will be a special part of the pre-game ceremony," the league said in a prepared statement. "It is an opportunity to honor our country and reflect on the great liberties we are afforded as its citizens. In respecting such American principles as freedom of religion and freedom of expression, we recognize the right of an individual to choose and participate, or not, in our celebration of the National Anthem."

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