Rihanna posts topless photos and Instagram takes them down, warning her via email that she might be banned altogether if she keeps violating the company’s sense of propriety.

Meanwhile, Instagram seems to see nothing wrong with rapper Chief Keef posting photos of himself and a pal brandishing a handgun and an AK-47.

Keef being a guy whose criminal record includes pointing a loaded firearm at a police officer.

He is also a guy whose lyrics and tweets deliberately stoke the flames of a gang feud in Chicago. The latest victims of that feud include a 16-year-old boy and a 17-year-old girl.

In the aftermath of the girl’s death, her pals posted a half-dozen photos of her brandishing guns. Instagram did nothing to take them down.

Imagine how Instagram would have reacted to photos of a girl that age posing not with a gun but without a shirt.

A photo that Instagram did take down was one that Canadian artist Petra Collins posted of her lower half in a swimsuit. Her unforgivable sin: an unshaven bikini line. Instagram actually suspended her account because of it.

But there would have been no problem if she had concealed the unrazored fringe with a Glock.

Maybe Rihanna should cover her offending nipples by cradling an assault rifle such as the one Chief Keef’s pal sports in the photos that Instagram finds acceptable.

By permitting gun photos, Instagram and its parent Facebook help foster a culture in which young people settle their differences with bullets.

While Keef and his pals post their gun photos, his “opps”—opposing gang members—post a variety of their own. And many of those pics have been up for a year or more.

One photo that has been posted since November shows a smiling kid who looks to be about 13 pointing a big automatic pistol at the camera.

“Shots fired on yall…WE KILL NI**AZ & BITCHES,” reads the message below.

A photo that has been up for more than a year shows youngsters who appear to be around 14, with one kid pointing an automatic pistol, another kid displaying a Tech-9 submachine gun as he sports a T-shirt bearing the likeness of 17-year-old Rodney “Trell” Stewart. Trell had a bus ticket to Iowa and the promise of a new life in his pocket when he was fatally shot in a Chicago alley in 2012.

“R.I.P. Trell,” says the young gunman’s T-shirt.

There is also a photo of a man sitting with a pistol in his lap as he loads an AK-47.

“NOW ITS TIME TO CATCH BODIES FOR JOJO,” reads the blurb next to the photo, JoJo being a rapper who was also shot to death in 2012.

In several photos, the subjects are topless, but they are all males. And they are only brandishing firearms, which is within Instagram and Facebook standards, even if you are holding a gun in each hand, as several kids do.

Apparently, nipples speak of sex to Instagram, which seems to view sex as shameful.

Somehow guns in the hands of kids do not speak to Instagram of violent death.

Anybody who has seen a youngster dead from bullet wounds has witnessed what is profoundly obscene.

Meanwhile, the photos that are posted thanks to Instagram and Facebook include one in which a teen in a plaid hoodie clutches a big revolver in his right hand and an automatic pistol in his left.

“Looking good,” reads a comment.