It's called the "Ice Bucket Challenge" - where participants either pour a bucket of ice water on their heads or donate to ALS research and then nominate three more people to complete the same challenge within 24 hours.

The challenge was launched by the ALS Foundation to raise money for children fighting ALS, also known as Lou Gehrig's disease. According to the Associated Press, the ALS Foundation has raised nearly $4 million since starting the challenge on July 29.

The trend has become very popular amongst celebrities, and the latest to join the trend is singer Justin Timberlake, who accepted the challenge from two Boston bombing survivors, Patrick Downes and Jessica Kensky. The "Mirrors" singer posted a video online of himself and The Tennessee Kids completing the challenge.

Timberlake then nominated Jimmy Fallon and The Roots to take the challenge.

"#ALSIceBucketChallenge. Thanks #PatrickDownes & #JessicaKensky for nominating me and The Tennessee Kids. We now nominate 'The Tonight Show Starring Jimmy Fallon' and The Roots...You've got 24 hours to donate AT LEAST $100 or douse yourself with ice. (Or both. We did both...and then we donated a bunch more. It's such a good cause.)," he wrote along with adding the link to donate.

Other celebrities that have been doused with a bucket of ice water include  Lance Bass, Martha Stewart, Matt Lauer, Kate Mara golfer Greg Norman and New Jersey Governor Chris Christie