Lionel Messi. Benedict Cumberbatch. Lebron James. Who wouldn’t want to see them in wet T-shirts?

For a few weeks, the world has been feasting its eyes on celebrities standing awkwardly in front of a camera before a bucket of ice water is dumped on their heads. These viral clips are just a small sample of the ALS Ice Bucket Challenge archive. While presidents and puppets have all made appearances, legions of ordinary social media users have also taken the challenge, supplanting cat videos on newsfeeds everywhere.

The rules of the ALS Ice Bucket Challenge are surprisingly hard to pin down considering how many people have taken the plunge, but it boils down to a simple dare: either donate $100 for ALS research or have a bucket of ice water dumped on your head. As the campaign has grown to global proportions, the rules have morphed such that most people are both donating and getting wet, then encouraging three friends to do the same.