Rapper 50 Cent is being investigated by the NYPD over an Instagram post that appears to threaten a Brooklyn precinct boss accused of shaking down a hip-hop club, The Post has learned.

“Get the strap,” Fitty told his 18.1 million followers on Wednesday — a catchphrase he uses at the end of many of his posts on the social media site. He was apparently referring to Deputy Inspector Emmanuel Gonzalez, head of the 72nd Precinct in Sunset Park, following stories about the police boss allegedly squeezing the owner of the Love & Lust club for gifts, including free round-trip tickets to Puerto Rico.

“Strap” is street slang for gun.

The NYPD is investigating possibly charging Fitty with misdemeanor aggravated harassment, which alleges a threat to cause physical harm.

“There is a formal complaint on file for Aggravated Harassment and detectives are investigating,” an NYPD spokesperson said.

Fitty’s reps, though, are countering that the rapper has repeatedly used the phrase as a “playful” jibe.

“Get The Strap” is a playful phrase used by Mr. Jackson to punctuate absurd and outrageous situations,” said rep Amanda K. Ruisi, using the rapper’s given name, Curtis James Jackson III.

“They trying to shut him down,” the rapper posted on Instagram of Love & Lust owner Imran Jairam, who has put the NYPD on notice of his intent to sue for $125 million over his claim that Gonzalez unfairly targeted his club for inspections in order to squeeze him for perks.

“Oh no not LUST,” Fitty (given name Curtis James Jackson III) wrote of the club, an apparent favorite of his.

Fitty tagged the club owner, @stardnr, in his post.

The rapper’s apparent call to arms inspired a fusillade of threats from his followers — prompting Gonzalez to file a police complaint against Fitty.

Gonzalez “is annoyed, alarmed, and is in fear of his safety,” according to a criminal complaint filed with the 72nd Precinct that was obtained by The Post, which names the CO as a “complaining victim.”

“Comments included, but are not limited to, ‘Get the strap’ multiple times, [and] ‘F—k this commander has to get the strap ASAP,’ ” the complaint said.

The aggressive posts were still up Thursday afternoon.

“Get the strap,” followers jimmykamara and carlarfowler echoed of Fitty’s apparent threats against the CO.

“Get the strap on them,” agreed tee_vybz_247.

“Say it ain’t so brother!!!! Get the strap!!!!” joined in m_wish_parkslope.

“Get da burner broski,” posted squeezyweez416, using another slang word for gun.

“They are taking this seriously,” a high-ranking police source told The Post of the NYPD.

The violence-tinged catchphrase shows up nearly daily on 50 Cent’s Instagram.

The rapper even last month applied to the federal Patent and Trademark Office, in hopes of trademarking the phrase for use on hats and t-shirts.

But it’s got the notorious Internet troller in hot water before. Just last week, VH1’s Love & Hip Hop star Teairra Mari threatened to sue Fitty for reposting her leaked sex video under the caption, “Get the strap.”

“We consider ‘Get the strap’ to be either a threat of violence or encouraging violence against this revenge porn victim,” Mari’s lawyer, Lisa Bloom, told The Post.

“It either means get a belt to assault someone with, or it’s slang for a gun. Either way, it’s a very scary phrase, especially considering he has 18 million Instagram followers,” Bloom said.

“He wants to put it on hats? Are you kidding me?” she added when told of the trademark application. “I think it’s appalling.”

In April, Fitty taunted “Get the strap” in response to rapper Hell Rell getting jumped at an unnamed restaurant. Hell Rell reportedly responded with an Instagram live stream in which he warned Fitty, “Don’t push me,” and aimed what looked like an assault weapon at the camera — getting, literally, the strap.

“Months ago, Curtis ’50 Cent’ Jackson filed to trademark the phrase ‘Get The Strap,’ a slogan he has been posting across all of his social media platforms,” his rep said in a statement.

“It is posted in connection with photographs and videos, including many featuring just him or things he is promoting.

“Taken in its proper context, the specific post in question was neither intended as, nor could reasonably be interpreted as a threat or call to violence against anyone.

“So the record is clear, Mr. Jackson does not condone or promote the use of violence against anyone.‎ ‘Get The Strap’ is a playful phrase used by Mr. Jackson to punctuate absurd and outrageous situations.”

Additional reporting by Laura Italiano

This article originally appeared in Page Six.