What started out as a social media joke has become an accidental campaign for breast cancer awareness – resulting in women (and some men) going topless for the ’cause’.

Las Vegas-based model Gemma Jaxx said there was no charity element attached to the #HoldACokeWithYourBoobsChallenge, which she started with a colleague to poke fun at other social media ‘challenges’ like the ‘Kylie Jenner lip challenge‘.

The #HoldACokeWithYourBoobsChallenge involves people snapping photos of themselves with bottles or cans of Coke between their breasts, the glamour model said.

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But somewhere in cyberspace the trend soon became a way for people to raise awareness about breast cancer – with people and celebrities stripping off and taking selfies after falling for the social media joke.

Melbourne’s Kiis FM drive show co-host Kate Langbroek took the challenge and posted it to the radio show’s Twitter page, less than a month after speaking publicly about her son’s leukaemia battle.

For a great cause #HoldACokeWithYourBoobsChallenge @hughesyandkate http://t.co/5zBDMSsTkg pic.twitter.com/6BL5swcOzf

— KIIS 101.1 Melbourne (@kiis1011) June 3, 2015

The #HoldACokeWithYourBoobsChallenge is the sexiest breast cancer awareness campaign to date – http://t.co/zaiJXb02aX pic.twitter.com/4TMMe41y7J — Playboy (@Playboy) June 3, 2015

Şimdi onlar düşünsün !!! Get over it !!!#HoldACokeWithYourBoobsChallenge pic.twitter.com/p8mGS5bTaM

— Beyaz Yakalı (@beyazyAQali) June 3, 2015

Ms Jaxx posted different ways to hold a Coke can in her breasts on her Facebook page.

But the trend drew criticism from some Twitter users about how insensitive the so-called ‘campaign’ was, accusing it of trying to make cancer seem “sexy”.

Ms Jaxx said now the joke had become about a serious issue and people should be able to take part if they wanted to.

“We never thought it would take off like it did. But it did. And then people started posting it was for charity and it was for breast cancer awareness,” Ms Jaxx wrote on Facebook.

“We had never plan (sic) on that nor thought of it.

“But since that’s what people want to do it for, we said why not do something good with this. So we went with it.”

“They can ether (sic) do the challenge, donate to their favorite charity, or both. It’s up to them.”

Most Twitter users just had a good laugh about the concept.

Have you heard about the #HoldACokeWithYourBoobsChallenge? It’s not a fundraiser, but I had to try…and fail. pic.twitter.com/qQlfyS3Cfk — Q102 Philly (@Q102Philly) June 4, 2015

Je pose ça là. #HoldACokeWithYourBoobsChallenge pic.twitter.com/igKS4evG6M — Brice Duan (@Brice_Duan) May 23, 2015