By the time most of us finish kindergarten we’ve learned a basic life lesson: If you dish it out, you better be able to take it.

Clearly the mainstream media — full of crybaby adults — have forgotten this.

They maliciously smear President Trump 24/7 on their airwaves and attempt to delegitimize his administration on every available media platform, then play victim when the president indulges in a basic human reaction — self-defense — and accuses the media of trafficking fake news.

The left-leaning mainstream media have always maligned Republicans, that’s nothing new. They went after Mitt Romney for his “binders full of women” gaffe — when he had a strong record of hiring women at high levels — and countless other GOP candidates. But with Trump they’ve gone to unethical extremes, defaming him at every turn since the day he announced his candidacy for president. A cabal of media and politicians have fueled the absurd claims that he is a racist, a liar, a misogynist, unhinged, a clown and worthy of being compared to Hitler.

And that’s just before breakfast.

This is a man who built a multibillion-dollar corporation, creating tens of thousands of jobs, and promoting women into key positions, and now has been elected president — an outcome they refuse to accept.

Yet by the time viewers reach lunchtime watching most TV channels today, our president has been smeared with specious suggestions of criminality and corruption ranging from phony Russian collusion to countless other manufactured crises and scandals that are concocted for one sole purpose — to take down our president.

What elected leader can operate under such a hostile work environment?

Undoubtedly the rigged media — which shamelessly ran defense and ignored scandals for President Barack Obama and candidate Hillary Clinton — are largely to blame for the lack of civility and unity in our country. They’ve unabashedly fanned the flames of divisiveness by constantly attacking our president.

CNN alone has retracted four major fake news stories in just the past month. Now consider the magnitude of the smear campaign against a sitting president when you add in all the other Trump-hating left-leaning news outlets nationwide. It’s no wonder Trump is fighting back.

He is victim to the most vile and dishonest disinformation campaign in history — pushed by unethical, partisan media acting in the interests of the Democratic Party.

With all the political violence we’ve seen of late — from anti-conservative rioting on college campuses to an assassination attempt on GOP members of Congress — this must stop.

Meanwhile, Americans should change the channel. When outlets lose ratings and their almighty advertising revenue they’ll get the message.

Adriana Cohen is host of “The Adriana Cohen Show,” heard Wednesdays at noon on Boston Herald Radio. Follow her on Twitter @AdrianaCohen16.