Real time picture chatting service Snapchat is designed to be ultra private. Photos taken and sent with the service can only be viewed for a maximum of 10 seconds before disappearing forever, but as it turns out, those images might not be so temporal after all.

While Snapchat has a built-in function that notifies a user if asent picture has been stolen via a screenshot, there’s currently a workaround that allows people to take screenshots without setting off that particular alert.

The workaround may be how two freshman girls at Ridgewood High School in New Jersey ended up finding naked photos of themselves on Instagram. According to Mashable, the teens sent photos of themselves to at least one male classmate, who took screenshots and shared them.

Secretly taking a screenshot of a Snapchat photo is surprisingly simple. As you take a screenshot by holding down both the power button and the home button, simply place a finger on the screen.

After the screenshot is taken, double tap on the home button, returning to the camera. This allows users to capture a screenshot without sending a notification because the iPhone’s multitasking bar interferes with the way that Snapchat detects screenshots.

This hack was originally published in January, but the situation in New Jersey makes the warning worth repeating: Your Snapchat photos are far from private.

The culprits in New Jersey, if found to be in possession of the nude photos of the girls, might face child pornography charges. Creating, transmitting, or possessing sexually explicit images in New Jersey violates both child pornography and “Endangering the Welfare of Children” laws, which carries a hefty penalty.

The lesson here? Think twice before you send a questionable photo via Snapchat, and think twice before you save one too.