This may just be the most unique approach to the Ice Bucket Challenge yet!
Olivia Wilde helped raised awareness for ALS on Saturday by posting a video of herself completing the challenge ... and substituting ice cold water for freezing breast milk.
"I hope it's ok, I couldn't find any water so I'm going to use breast milk," she says in the clip. "It took me all night to make this."
Wilde is an outspoken supporter of breastfeeding -- and even posed with her son Otis while doing it in Glamour for the September issue.
"I don't know, now it feels like Otis should always be on my breast," she tells the mag. "Breastfeeding is the most natural thing."
Check out her video below -- and click here to see more stars who have completed the Ice Bucket Challenge, which has already raised $70.2 million so far.