Marcus Mabry is senior director of mobile news programming at CNN and author of "White Bucks and Black-Eyed Peas: Coming of Age Black in White America." He has written about race for The Source, The New York Times and Newsweek. The opinions expressed in this commentary are the author's own. View more opinion articles on CNN.

(CNN) It's not surprising that a New York weatherman saying a racial slur on television ignited a controversy that ripped through social media. It is not surprising to some people that the incident led to the weatherman, Jeremy Kappell of WHEC in Rochester, New York, being fired.

What is surprising to many is that the antique Southern anti-black slur, coon, is often substituted for King in the name of the civil rights icon Dr. Martin Luther King Jr.

But many African-Americans are familiar with exactly that swap: Martin Luther Coon Boulevard, Martin Luther Coon Park, Martin Luther Coon Day, Martin Luther...

In fact, despite what many Americans assume, King is not universally respected or admired. Thirty-five years after Ronald Reagan signed the bill making King's birthday a federal holiday, there are those who still resist it.

In the firestorm that engulfed social media, people have rushed both to condemn Kappell and to defend him and criticize his station for firing him.

Would-be linguists have weighed in on both sides. One side saying Kappell either intentionally used the phrase, or that he slipped only in the time and place that he said it, but it must have been a part of his regular vocabulary.

"wowww that video. he definitely says that all the time, which is why it slipped out on air," said Twitter user @notmuchelse.

"Are you kidding me? That's one of the dumbest things I've ever heard. Say 'King' and 'Junior' 5 times fast and tell me what happens," responded another Twitter user with the handle @JaredG_13_.

Are you kidding me? That's one of the dumbest things I've ever heard.



Say "King" and "Junior" 5 times fast and tell me what happens.



It's a very easy mistake to make. Granted not one that should be taken lightly, but also not one you fire someone over with no explanation. — Jared (@JaredG_13) January 8, 2019

Kappell insisted he simply "jumbled" his words. "There was no malice," he said in a Facebook video on Monday, "Some people did interpret that the wrong way. That is not a word that I said. I promise you that." He meant he did not intentionally say the word "coon," but jumbled together the k-sound from King with the "oo" sound from "junior." He said he often speaks quickly in his weather reports.

"I would never want to tarnish the reputation of such a great man as Dr. Martin Luther King Jr., one of the greatest civic leaders of all time."

"I've probably said Martin Luther King Jr. a thousand times or more in my career," he told The New York Times in a phone interview. "To my knowledge, this is the first time that it came off wrong."

In response to a Twitter user who charged that he made the slur intentionally, he railed, "You are out of your mind to think I would jeopardize future of my family and career to insert a racial slur against the GREATEST civil rights leader of all time?!?! #Ridiculous #Hateful #Judgemental and #youdontknowthefirsthingaboutme!"

You are out of your mind to think I would jeopardize future of my family and career to insert a racial slur against the GREATEST civil rights leader of all time?!?! #Ridiculous #Hateful #Judgemental and #youdontknowthefirsthingaboutme! https://t.co/pjlBIaKGhE — Jeremy Kappell (@JeremyKappell) January 7, 2019

We may never know what is in Kappell's heart. But the strong response to the slur, whether intentionally uttered or not, and the speed of his station's firing him -- two days after his remark -- show the powerful emotion around the slur and casual, offhand utterances like it.

Casual racism is such a common occurrence, it's like the air we, people of color, move through. There are "microagressions," slights or assumptions that were not even acknowledged enough to have a name in previous generations -- the same way routine harassment was tolerated prior to the #MeToo revolution. There are institutional biases that afflict the places we live and work. And there are entrenched societal prejudices that affect the medical care we receive and how police protect us, or not.

That's why some social media users found it so easy to believe Kappell must use the c-slur "all the time." People who had never met him had heard casual racial slips too often.

Kappell appears to be sincere in his Facebook video and in his stated admiration for King.

But the constant exposure to racial slights, big and small, the daily assault, and to the way non-black people refer to some of the places where we live and go to school, rubs nerves raw. And when a slight is made publicly, the hurt leads to demands for repair.

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The debate on social media has moved predictably to whether Kappell's firing makes him a martyr of political correctness.