KENNETH screwed up. The 11th grader made a crude joke about the police officers in his Bronx high school — and an officer overheard.

“What did you say?” the officer demanded. “Say it again and I’m going to punch you in the [expletive] mouth.”

“You can’t [expletive] touch me,” said Kenneth, who has Asperger syndrome.

And so it began ...

The officer pulled out his nightstick, with one hand, grabbed Kenneth (whose name I’ve changed) by the throat with the other, and pushed him against the wall. Then he pinned the boy’s arms behind his back and pulled him, by the neck of his hoodie, down the fourth-floor hallway.

The officer, who said Kenneth pushed him, arrested Kenneth and drove him to the local precinct, where officers took his photo and his fingerprints, and detained him overnight in a locked cell.