We've had 'no make-up selfies' and the ice bucket challenge – but the latest campaign taking social media by storm has been criticised for trying to make breast cancer sound "sexy".
Many women have already taken part in the #HoldACokeWithYourBoobsChallenge, snapping photos of themselves with bottles or cans of Coke between their breasts, with their nipples subtly - and sometimes a little less subtly - covered up.
But some people criticised it for making breast cancer seem "sexy".
Others took to Twitter to denounce the challenge as "unhealthy".
Now I've seen it all.. #HoldACokeWithYourBoobsChallenge is really a thing. I held milk with mine, far healthier than Coke psshhh.; Jami (@Jami_USA) June 3, 2015
And some used it as an excuse to poke fun at those taking part, with men getting in on the act, too.
It comes amid revelations that the challenge was started by an adult modelling agency.
Gemma Jaxx, a model, took responsibility for the hashtag - which she said she thought up alongside a colleague, Danny Frost, to "make fun" of other challenges - like the 'Kylie Jenner lip challenge' and the 'step on the flag' challenge - and wasn't anything to do with charity in the first place.
She wrote: "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. 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."
Ms Jaxx then called for people to challenge their friends to take part. "They can ether [sic] do the challenge, donate to their favorite charity, or both. It's up to them."
And she had a message for her critics: "Keep in mind that when we started this, it had nothing to do for cancer, but that the people who were taking part in it wanted it to be.
The most controversial internet crazes
The most controversial internet crazes
1/7 Gun Selfies
Where it actually came from remains a mystery, but the 'Selfie' remains a popular feature on the internet - it was even named word of the year by Oxford Dictionaries in 2013. However, a number of gangs in America have taken it a step further, posting 'gun selfies' of themselves. Last year, two men were charged for 142 counts of possession of a firearm and were bailed by police after posting numerous photos. The craze has led to several calls for photos to be taken down, with parents fearing that children could try and create their own poses.
Originating in Australia in 2008, the trend of 'planking' swept Britain a year later. The craze, in which people form a straight figure with hands down by their sides, had thousands of participants uploading their efforts on to Facebook. While most were harmless enough, the more daring have been known to plank across railway tracks and between buildings, causing major health concerns. In 2011, a 20-year-old man died after 'planking' on a seven-story building in Australia.
Twerking, a mixture of twisting and jerking, has been around since the late 1990s, but its popularity dramatically increased after Miley Cyrus 'twerked' at the 2013 MTV VMA awards with Robin Thicke, prompting fans to upload their own versions on Youtube - we've even had twerking stormtroopers. It's since been accused of corrupting the minds of young people and, last year, 33 students were suspended after making a video of themselves 'twerking' using school equipment.
4/7 Happy Slap
It's been almost a decade since the Happy Slap craze broke out in the UK, but what started out in as a small joke between friends in Lewisham in 2004 eventually became a nationwide phenomenon. Happy Slapping involved a victim being filmed on a camera phone getting slapped. As the craze spread, incidents became more and more vicious and it was linked to a rise in bullying in school playgrounds. In 2008, a teenage girl was sentenced to two years' detention after filming the fatal beating of a man.
'Tombstoning' emerged in 2012 as a much more dangerous fad. It involved finding the highest rock to leap from, giving jumpers sufficient time to change their body position to resemble a tomb falling into the sea. It was invented initially as a way to keep cool during sizzling temperatures, but as the challenges became more daunting, some experienced horrific injuries as a result of jumping into shallow or rocky waters.
While not as dangerous as other internet fascinations, McDonald's staff are now finding themselves on the receiving end of another internet craze. 'McDiving' started last year and normally comes at the end of an alcohol-fuelled night out, where it is then customary for a 'McDiver' to go to the nearest McDonald's and launch themselves over the counter. McDonald's franchises have even started hiring bouncers at peak times of the day to deal with any mischief makers.
7/7 Gallon Smashing
Given that glossy floors are prominent in supermarkets, it would be deemed acceptable to see the occasional person slip over. But this is no accident. Gallon smashing started to appear on Youtube last year and has becoming increasingly popular in the US. It sees agile teenagers throw gallons of milk in the air as well as hurtling themselves on to the ground. However, with the mess, cost and inconvenience that is caused, the 'gallon smashing' craze has seen security stepped up in supermarkets.
"Let's face some real facts. Not every woman does their exams or goes and gets a mammogram. Several people are on the mind set it will never happen to me, I'm to [sic] young or old for it to happen to me, my boobs are too small... and so on and so on...
"So if this gets a few of those types of girls to do their check ups and prevents them from losing their breast or dying from breast cancer by doing something fun and goofy, does it not make it worth it?
"If one girl, Just one if not more, life was saved because she felt something in her breast when she did this challenge, isn't it worth it?"
Danny Frost, of Elite Talent Referral, the adult talent-scouting company behind the campaign, told Bash Feed: "It grew into something for a good cause. When people started posting that it was for charity, we then decided to go with it, and said why not?
"We tell people to get their mammograms and to donate to any breast cancer charity they want too [sic]."
A Breast Cancer Care spokesperson told The Independent: “It is brilliant that the internet and social media give people the tools and opportunity to create their own campaigns to raise awareness and funds for charities. But this is not a campaign we are involved with."Reuse content