The Ice Bucket Challenge is fast proving to be no mere Internet meme or simply the latest in a long line of stupid human tricks to clog up your Facebook feed. Having raised more than $3 million for its cause and even crossing the desk of the President (he politely declined the ritual, offering a donation instead), it’s a certifiable phenomenon and a case study in public health awareness. In the off chance you've been living under a — er — bucket for the last few weeks, the Ice Bucket Challenge goes like this: you pour a bucket of ice water over your head and challenge someone else to do the same in the next 24 hours, all in the name of raising money for amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease. Celebrities across the cultural spectrum — Oprah! Lady Gaga! Bill Gates! — have taken part, and the momentum shows no signs of cooling. Check out some of our favorite celebrity dousings below. Did you take the challenge? Who would you nominate?