A man touches a woman's breast following the midday Chupinazo rocket announcing the start of the San Fermin festival in Pamplona July 6, 2014.
A man touches a woman's breast following the midday Chupinazo rocket announcing the start of the San Fermin festival in Pamplona July 6, 2014. Tens of thousands of expectant party goers holding red scarves squeeze into the town hall to kick off 204 hours of music, dancing, drinking, bullfighting and for the brave or unwary, an 825 metre (902 yard) daily sprint in front of six fighting bulls known as the Running Of The Bulls. REUTERS

Is Lady Gaga joining the "Free the Nipple" campaign through Instagram? It apparently seems to be the case after she posted a revealing selfie on her account where one of her nipples had managed to slip into sight.

The photo was posted on Friday, July 18 according to E! Online. The pop diva was aboard a plane wearing a low cut white dress with a hefty gold necklace when she decided to take a selfie. One of her breasts managed to get a peek at the camera as well when it was captured on the photo. Lady Gaga then captioned the photo "FASHUN: Vintage Mugler on the plane Listening to Miles Davis My favorite is Flamenco Sketches."

The singer must have noticed the accidental flash since she had reportedly deleted the photo right away. The said nipple slip photo was also posted to her Facebook page and has since been deleted too. The 28-year old was reportedly on a private jet bound for the Yellowstone Club in Montana to discuss some art as revealed through her other Instagram photo.

Instagram has always been strict on their policies when it comes to users' posts. Its community guidelines according to E! state, "Please do not post nudity or mature content of any kind." However, several celebrities have opposed this guideline.

Demi Moore and Bruce Willis' 22-year old daughter Scout Willis bashed at Instagram's nudity policy by spearheading the "FreeTheNipple" campaign. In defiance, she walked the streets of New York completely topless. Miley Cyrus reportedly also posted her selfie with a rubber nipple on her Twitter page.

A previous report from IBTimes also noted another Willis who is also supportive of the "FreeTheNipple" campaign. Scout's sister, Rumer Willis, joined a PSA about normalizing breastfeeding photos along with Soko, Tyler Jacob Moore and Kim Allen in support of the campaign.

The "Free the Nipple" campaign targets Instagram's policy against female nudity. E! added it aims to fight censorship against the female body's discrimination.

Later in the day, Lady Gaga, who has been known to dress in risqué outfits, tweeted what E! suggested was her reaction to the nipple slip.

Where is the face palm emoji when u need it