The ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease) Ice Bucket Challenge is basically an activity involving dumping a bucket of ice water on one’s head or donating to the ALS Association in the United States. The rules state that the nominated participants are required to have a bucket of ice water poured on their head within 24-hours and / or donate money to charity should they decline.

5. Robert Downey Jr.

The origins of the idea of dumping cold water on one’s head to raise money for charity are unclear and have been attributed to multiple sources. During the Northern-Hemisphere winter of 2013-14, a challenge of unknown origin often called the “Cold Water Challenge” became popular on social media in areas of the Northern United States. The task usually involved the option of either donating money to cancer research or having to jump into cold water. It was criticized for the danger of going into cold water unassisted.

4. Tom Hiddleston

The earliest known version of this challenge was known as the “Cold Water Challenge.” It was started by the Sheaves For Christ division of the General Youth Division UPCI. A video dated April 26, 2014 by Amado Huizar challenges others to donate 100 dollars to the SFC Missions fundraiser or jump into cold water. Many videos followed of people dumping buckets of water on people’s heads.

3. Vin Diesel

One version of the challenge started in New Zealand on July 4, 2014, with a fundraising page on behalf of the Cancer Society to help support patients and their families through the trauma of a cancer diagnosis. As with similar challenges, it was usually filmed so footage can be shared online.

2. Chris Pratt

The challenge was popularized in the United States on June 30 2014 when the Golf Channel Morning Show televised the social media phenom and performed a live on-air ice bucket challenge.

1. Charlie Sheen

Barack Obama, was challenged by Ethel Kennedy but declined, opting to contribute to the campaign with a donation of $100. Justin Bieber, LeBron James, and “Weird” Al Yankovic also challenged President Obama after completing the Ice Bucket Challenge.