Stars chilling out for charity
David Beckham did it topless. Lady Gaga performed it in her signature quirky style. Bill Gates did it in slow motion. And Vin Diesel put the challenge to Vladimir Putin.
The #IceBucketChallenge is the latest charity craze to take the internet by storm, with people pouring iced water over their heads in a bid to raise money for charity.
Sport stars, international celebrities and it seems, everyone else, are posting videos of their chilly challenge on social networking sites and the trend has raised thousands of pounds for cancer and motor neurone disease charities.
Macmillan Cancer Support said 85,000 people have donated so far and about £250,000 has been raised, and while t he Motor Neurone Disease (MND) Association was not able to give a figure at this stage they said they had received "a lot" of donations overnight and the total so far is believed to be in the thousands.
Meanwhile, in the US, the ALS Association - a motor neurone disease charity network - said it had received 22.9 million US dollars (£13.8 million) in donations compared to 1.9 million US dollars (£1.1m) during the same time period last year (July 29 to August 19).
Golfers Rory McIlroy and Tiger Woods did it together, taking it in turns to pour the iced water over each others' heads.
McIlroy challenged fellow sports star Wayne Rooney to do it, and Rooney's wife Coleen posted a picture of a bucket full of ice on Twitter this morning.
The Irishman also challenged George W. Bush to take part, while Woods challenged tennis player Rafael Nadal.
A giggling Simon Cowell appeared to be on a boat in a sunny destination when he did the deed, and through his giggles he nominated X Factor judges Cheryl Fernandez-Versini, Louis Walsh and Mel B.
Other big names to have stepped up to the challenge include Facebook founder Mark Zuckerberg, footballer Cristiano Ronaldo, Oprah Winfrey, Britney Spears and Justin Bieber, with the latter nominating US president Barack Obama.
Also enduring the shiver-inducing splash were models Cara Delevingne and Suki Waterhouse, while Good Morning Britain hosts Susanna Reid and Ben Shephard got drenched live on air.
Sally Light, chief executive of the MND Association, said the craze was an "unprecedented opportunity to raise awareness of what is a devastating terminal disease".
She added: "We care for thousands of people affected by MND across England, Wales and Northern Ireland but we also fund global research.
"The amazing sums of money being donated across the world and with sister organisations in the USA and Australia too will go a long way towards finding out more about the disease for which there is no current cure."
To take part, people need to have their experience filmed and then share it via sites such as Facebook and Twitter, challenging others to do it within 24 hours, before donating money to charity by text message.
You can donate £3 to Macmillan by sending ICE to 70550, and text ICED55 followed by an amount (such as £5) to 70070 to donate to the MNDA.
Macmillan said forfeiters can instead text FINE to 70550, donating £10 to give the icy dousing a miss.
The craze is similar to the #nomakeupselfie campaign earlier this year in which women posting bare-faced selfies online helped Cancer Research UK raise more than £8 million.
Cheryl has accepted Cowell's challenge and has posted a video of herself getting soaked on her Instagram account.
The pop star squealed as the water was poured over her and said: "I hope you're happy."
She challenged One Direction singer Liam Payne, Piers Morgan and fellow Girls Aloud star Nicola Roberts to get in on the action.
Meanwhile, Coleen Rooney has also posted a video online of herself taking part, with her husband Wayne giving her the soaking, and she too nominated Morgan.
The TV host posted links to the women's videos in a tweet, and said the two "smackdowns are noted & accepted".