Unsurprisingly, recipient charities are delighted but they are also wary of risks that come with online campaigns they have no real control over. That was underlined by the death of Northland man Willis Tepania from a heart attack, hours after having a bucket of icy water poured over him in the challenge. Tepania, 40, had reportedly drunk a large quantity of bourbon in a short time and had been in poor health for several years. No autopsy was done and cause of death has not been confirmed, but his death prompted comment about possible risks.
Dr Stephen Wealthall, who has studied sudden exposure of the head and face to cold water, cautioned that the game could kill even without alcohol being involved because of a protective reflex that closes the larynx, slows the heart rate and could stop a person breathing. "There is a chance some people will react very badly and that someone will die."
Another to have researched the response to sudden immersion in very cold water said though it could be risky for people with heart conditions, it was safe for the majority. Regular exposure could have benefits, says Chris Button, associate professor of the University of Otago's school of physical education, noting the success of Dunedin's annual polar plunge.
"I'd say it's probably not such a bad thing, you just have to think about doing it in a controlled fashion."
The ice challenge began some months ago in Florida, where firefighters dunked themselves to raise money for a local non-profit camp for kids who had lost their fathers in service to the country - the foundation is in honour of Aaron Vaughn, an Elite Navy Seal killed when a helicopter went down in Afghanistan in 2011. They posted videos online to encourage others.
If you were challenged to take part you could jump into a bone-chilling tub of water and pay $10 to the charity of your choice or decide against taking the plunge and donate $100.
Cold water became iced water and the challenge morphed into the Ice-Bucket Challenge and raced through the ranks of pro golfers, with stars including Rickie Fowler, Michelle Wie, Ian Poulter, Justin Rose and Ko joining in. For some, alcohol became part of it. In countless online videos, the exercise was conducted hand-in-hand with alcohol.
"It's a double-edged sword," Lynne St Clair-Chapman, Cancer Society national communications manager told the Herald. "Obviously we are humbled by the amount of money and that people have chosen the Cancer Society but on the other side, we have no control. It took us by surprise."
She said the Cancer Society posted on Facebook before Tepania's death urging participants not to combine it with alcohol and noted that alcohol was increasingly being linked to cancer. It also included medical advice explaining the challenge would put a load on the heart and shouldn't be done by people with heart problems or be combined with alcohol or drugs.
Amid the euphoria sparked by the windfall, the sector is debating how it can maximise the benefits and deal with the risks of viral campaigns.
By their nature, charities hand over the power and creativity to public whim and let them run wild with it.
"Scary," says Matt Collins, a British specialist in helping charities use digital channels to raise money. A core lesson of the campaign known by the hashtag #nomakeupselfie, was that the industry can't dream up such runaway successes.
"The truth is we have no idea what will catch on," Collins wrote on his blog (charitychap.com).
The no-makeup selfies campaign, for example, reportedly arose from a row at the Oscars and unwittingly harnessed the current obsession with selfies. Author Laura Lippman is credited with starting the trend to support actress Kim Novak, 81, after her looks were criticised at the awards. Participants posted a photo of themselves without makeup and challenged others to do the same by tagging them in the post. Early posts included the hashtag #beatcancer, so cancer charities encouraged participants to donate. Spin-offs included #manupandmakeup, as men put on makeup to raise money for Prostate Cancer UK.
Charities have to act fast to make the most of them. Making a decision in a few days' time means missing out, said Collins, but charities that opt in must be prepared for the inevitable bruises. Though the public was happy a lot of money was raised for charity, many didn't like the means. Reaction to the selfies campaign included the arguments that not wearing makeup was no sacrifice, it belittled those putting in real effort - such as people who ran a marathon - and that participants were egotistical.
It opened "the floodgates for more reductive, sexist, self-congratulatory campaigns for ominous gain", wrote Sali Hughes in the Guardian.
Charities wanting to ride these runaway trains need to decide how much negative reaction they are okay with, says Collins.
The Cancer Society plans to develop guidelines. "When no-makeup selfies started, we'd not dreamed of such a thing, or using social media to promulgate it," St Clair-Chapman says. There will be no-go areas. "If smoking was involved in a challenge or some other unsafe behaviour, we would say thank you but no thank you."
But hard and fast rules won't work and each viral sensation would need to be quickly judged on its merits.
Women posting pictures of their hairy legs along with positive comments is currently taking social media by storm. The motivation is to dispel common myths about what constitutes female beauty. At the time of writing there was no charity aspect to it but if there was, cancer charities would have to make a call given treatment of the disease often causes hair loss.
"What sort of things do we want to be associated with, what don't we want to be associated with, how to we say 'no thank you' nicely, all of these things are brand new to us."
The Breast Cancer Foundation received $80,000 from no-makeup selfies and $40,000 from the ice challenge. Spokeswoman Adele Gautier said donations began coming in with no impetus from the foundation until they became "clued in" and they started pushing the selfie campaign via social media mentions.
The foundation was more cautious about the ice challenge, she said, and did nothing to encourage it, in part because of reports about possible health risks.
"Overall, I think it's great," said Gautier. "People are doing something that really resonates. We can't force or create that as much as we would like to but people are finding something that works for them and are using it for good and are enjoying themselves at the same time, which is ideal."
More charities are likely to follow the lead of Cancer Research UK, which has a social media team, but Gautier says there is a long way to go in figuring out how to make it a significant and reliable moneymaker.
"There is a big gap in knowledge in how you translate social media interest and activism to money. It is a highly-powerful awareness and educational tool but converting that to dollars is a bit more of a mystery."
Debbie Thomson, national marketing manager for CanTeen, a charity that supports teenagers with cancer, can see online giving eventually becoming the most popular way of donating. "I think most charities in New Zealand would recognise that it is a growing market. These viral social challenges are a particular type of campaign that is not going to be sustainable ... but our online giving is steadily growing and I think as people increasingly expect to do everything online we are going to see a lot more income coming through online."
The $40,000 CanTeen has so far banked from the ice challenge is 0.66 per cent of its $6 million annual income, while the $189,000 the Cancer Society got from the selfie and ice campaigns is 0.94 per cent of its annual income of about $20 million.
Though the public might see fundraising simply as raising money for a good cause, charities see a bigger picture, says Fundraising Institute head, James Austin.
"Fundraising is all about developing a relationship with your donors. It is ongoing, a long-term commitment that might start off with them just helping out run an event or being a volunteer in a charity shop; it might start off at $5 a month but they may become stakeholders, so much so that at the end of their life they may even decide to leave a bequest in their will. That should be the aim."
Charities seek the disposable dollar and websites such as givealittle and viral campaigns are set up to target that, said Austin. The here-today-gone-tomorrow viral campaigns are easy, unpredictable and risky.
They could be considered just the icing on the cake but, as Gautier points out, "I think it is a big, thick, lot of icing - it certainly is not peanuts."