Als ice bucket challenge

WATCH: Oprah Winfrey,
Justin Timberlake,
Gwen Stefani & More
Stars Win the Best
'ALS Ice Bucket
Challenge' Award

Getty (3)

The "ALS Ice Bucket Challenge" has taken over social media!

In case you haven't heard, the challenge involves dumping a bucket of ice cold water over your head after being nominated. Once you accept the challenge, you have to nominate three others who then have 24 hours to accept.

The purpose of the nationwide phenomenon is to raise awareness and money for the ALS Association, which fights amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease.

If someone does not accept the challenge, they must donate $100 to the cause. To date, the ALS Association reports that it has received $4 million in donations in just two weeks.

We've rounded up some of the best videos we've seen so far of celebrities taking the challenge! Watch the videos below.

Best Scream After Dumping the Ice: Oprah Winfrey (LOL)

Nominated By: Tyler Perry

Famous People She Nominated: Steven Spielberg, Helen Mirren and Manish Dayal

Best Famous Person to Nominate: President Obama—Thanks, Justin Bieber!

Nominated By: Scooter Braun

Famous People He Nominated: Ellen DeGeneres, President Barack Obama and Chris D’Elia

Best Unexpected Video: Chris Pratt…“My butt crack!”

Nominated By: Bob Iger and Vincent D’Onofrio

Famous People He Nominated: Gregory Smith, Nick Offerman and Dave Bautista

Best Unusual Way of Accepting the Challenge: Carrie Underwood and Mike Fisher

Nominated By: Tons of people!

Famous People They Nominated: Jennifer Nettles, Shea Weber and Trevor McNevan

Best Dramatic Reaction: Taylor Swift…We think she’s still in shock.

Nominated By: Lily Aldridge and Ingrid Michaelson

Famous People She Nominated: Selena Gomez, Emma Stone and Ed Sheeran

Best SHIRTLESS Star to Take the Challenge: Stephen Amell…If only the video were longer (sigh).

Nominated By: Robbie Amell

Famous People He Nominated: Grant Gustin, John Barrowman and Jared Padalecki

Best Fashionable Star to Take the Challenge: Gwen Stefani…She would wear this!

Nominated By: Blake Shelton

Famous People She Nominated: Gavin Rossdale, Nicole Richie and Jessica Alba

Best Group to Accept the Challenge: Justin Timberlake and The Tennessee Kids

Nominated By: Patrick and Rescue the Dog

Famous People He Nominated: Jimmy Fallon, Steve Higgins and The Roots

Other Stars Who Accepted the Challenge: Robert Downey Jr., Lena Dunham, Jimmy Fallon, Selena Gomez, Blake Shelton, Adam Levine, Carson Daly, Joe Manganiello, Jamie Chung, Chloe Moretz, Jesse Metcalfe, Demi Lovato, Hilary Duff & More!

Click here to learn more about the challenge and donate to ALS.