It was business-as-usual at a Brooklyn barber shop — even as a customer was held at gun-point mid-trim.

Video tweeted by the NYPD Tuesday shows a gunman pointing a pistol at a man as he sits in a barber’s chair at Milton’s Barber Shop on Maujer Street around 4:30 p.m. Oct. 14 — with other customers casually ignoring the stick-up.

“Gimmie your s–t,” the thief said to the customer before stealing his iPhone and credit cards, police said.

The bandit puts his arms around the customer before sticking the gun to his neck — and the customer turns around just as his barber beings putting away his tools, video shows.

Then the barber walks around the two men and watches as the crook goes on with his business.

Nobody seems to notice the robbery, with one customer swiping away on his cell phone and another being led to an adjacent barber’s chair, the video shows.

“It all happened so fast,” said 27-year-old Luis Antonio, who was been snipping and buzzing at Milton’s for two years, “That guy came inside like he knew the guy (the victim) — he put his arm around him like he was hugging him, but he had the gun pointed at his neck.”

“The guy walked out the shop like nothing, he didn’t run he just walked straight through the doors of the projects across the street. Now that can damage the business. God forbid there would’ve been a child inside and a shot accidentally goes off,” Antonio added.

The thief fled in an unknown direction, cops said.