Intermediate 
George W Bush, Benedict Cumberbatch and Stephen Hawking have done it. David Cameron, Barack Obama and Pamela Anderson have refused to do it. The Ice Bucket Challenge began in the US in July and has raised $100m for the ALS Association, a US motor-neurone-disease charity, and 4.5m for a British one, as well as thousands more for charities in Hong Kong and Australia.
However, not everyone is happy with the Ice Bucket Challenge. Commentators, animal-rights groups and environmentalists have all criticized it, for reasons ranging from the waste of water to the fact that some people enjoy the fun and then do not donate anything to charity.
Meanwhile, the challenge continues to grow. For anyone who doesnt know how it works, someone gives a short speech to camera about the charity, then dumps a bucket of ice cubes in water over their head or gets a friend to do it. Then, they nominate three other people to either do the same or donate.
It was an unfortunate coincidence that 31 August to 5 September was World Water Week, with international delegates arriving in Stockholm to discuss the planets water crisis. The charity WaterAid is asking people to use recycled water from bathtubs or garden butts or to use sea water.
Douglas Graham, the UK Motor Neurone Associations fundraising director, said: The criticism is to be expected but, really, this is just a wonderful windfall and were so grateful. We didnt see it coming but, suddenly, the donations just started. The boost is an enormous help to a small charity looking after sufferers of a debilitating, little-understood disease that has no cure and kills five people a day in the UK.
Former Baywatch star Pamela Anderson, an animal-rights activist, wrote an open letter to the ALS Association, saying she could not support its record on animal experimentation. A few US stars have rejected the challenge because of Californias drought. Actor Matt Damon solved the problem by using water from his toilet. Actor Verne Troyer used milk, again saying it was for environmental reasons. And the challenge has been blamed for causing a water shortage on the Scottish island of Colonsay.
In Australia, a TV anchorman apologized over his strong no, thanks response to being nominated. Lincoln Humphries had said: Instead of pouring fresh water over your own head and wasting ice, here is a list of charities helping communities in desperate need of money across the world. Id like to nominate everyone, everywhere, who has more than they need, to donate what they can to the people who need it most ... because that is what charity is about, not putting yourself through mild discomfort with a bucket of icy water.
Another criticism has been that small charities wont be able to cope with the extra money, but the MND Association rejected this. Oh, we can cope here, said Graham. We fund world-class research into the causes of the disease to find a treatment or cure. We provide care and support for 3,500 people and they need it because this is such a rapidly progressing disease and its expensive to manage. Over 50% die within two years of diagnosis. Its heartbreaking to see the decline in people we work with over just a few months.
But, for many people with a connection to the disease, the awareness that the challenge has created is as valuable as the money. Graham says it is priceless. Normally, the MND Association gets around 300,000 hits a year on its website. On a single day recently, it had 330,000.
We couldnt have created this if wed tried. Charities are all worthwhile causes and I understand that some people might want to donate to a different one. In 2013, British people gave 62bn to charity  we should be proud of that. Its fabulous for us to get this windfall. Well be sitting down over the next few weeks to work out how to spend it in the best way but, I assure you, every penny will count for good.