Viral video shows the moment an enraged man slugs a woman in the face in a crowded Big Apple subway car – after she tells him to take a "chill pill."

The disturbing incident – initially posted on TikTok and reshared on Twitter Wednesday, where it’s received 2.4 million views – unfolded on a D train, though the exact date and location are unclear. 

The footage begins with the man standing over the woman, who was sitting down, yelling, "Say it to my face now! Tell me to take a chill pill! Say the word, ‘chill pill.’" 

"Chill pill," she replies, looking him in the eye.

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He immediately socks her in the side of the face – as people in the car gasp. 

"You wilin’, she a female!" the filmer says. 

"Mind your business – say it again," the man threatens the woman again as he moves away. "I’m dealing with my f---ing kids, you understand?"

He then launches into a tirade, addressing the whole train car, ending with, "When I’m standing on the train, move out the way!"

The video doesn’t show what led up to the act of violence.

The assailant "was already tight off life" when he got in the train car, and was "telling ppl to gtfo him & his kids way," the original poster wrote. 

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"All [the woman] said was he needs a chill pill & his kids repeated it to him and it was just up from there." 

The NYPD told The Post it is "aware of the incident" and is "investigating the assault." 

However, the victim never came forward to report the incident, police sources said.

Click here to read more on the New York Post.