Matt Damon may be the co-founder of charity Water.org, but it did not stop him from taking part in the ALS Ice Bucket Challenge.
Nominated by his long-time friend actor Ben Affleck and comedian Jimmy Kimmel, the Hollywood star used the challenge as an opportunity to highlight the plight of 800 million "without access to clean water", by fishing out water from every toilet bowl in his house.
Speaking ahead of the viral phenomenon, Damon said:
[The challenge] posed kind of a problem for me, not only cos there is a drought here in California but also I co-founded Water.org and we envision a day when everybody has access to clean drinking water...so putting a clean bucket of water on my head seemed a little crazy.
The activist then nominated his favourite actor George Clooney, his favourite musician Bono and the "greatest quarterback of all time" Tom Brady to take part in the challenge.
Leonardo DiCaprio also had an environmental response to the challenge, who is in Canada working on his documentary Carbon about the impact of climate change and carbon emissions.