Originally, the ice bucket challenge was not associated with ALS.
Before it all went viral, I saw a number of my capoeirista friends taking part, and the challenge was a little different, have two buckets of iced water poured on you, then pour the third one on yourself (here's my capoeira teacher, Mestrando Primo taking part, just before it went viral).
The idea for the challenge was to either take the challenge, or donate to charity (or both), and to pick a charity of your choice, and also nominate three more to take part. Now some would say this isn't the nicest of fundraising tactics, and that it amounts to bullying fundraising tactics, but I think it's not that bad (and certainly better than "trick or treat" at Hallowe'en which is essentially demanding money with menaces), Anyhow...
Facebook data indicates that the challenge started around June 8th, but it wasn't until August that it really went viral. Golfer Chris Kennedy nominated the ALS foundation, and this is where the association with ALS (aka Motor Neuron Disease, or Lou Gehrig's disease).
As with many charity things, some people have been critical of how ALS Foundation spend their funds, for example, they have $6.7 million in investments. What people often fail to realise is that charities need to have money in reserve - fundraising isn't always predictable, and if the fundraising dries up, you need to have your operating costs to carry on the services you provide. I've defended charity spending before, but it bears repeating: charities don't get anything for free, and if you want to have a professional bunch of people working for you, you will have to pay them, as everyone has bills to pay and needs food to eat.
The ALS Foundation are quite open about their spending, and in the UK you can go to the charity commission and look at the accounts of all charities. It is then up to you to see if you think a charity spends too much on its staff etc relative to how much the charity brings in. In the case of ALS, 21% being spend on fundraising and admin seems more than acceptable.
Any how, here's my ice bucket challenge: