Matt Damon has gone on strike -- from using the toilet.

In a humorous PSA to help support Water.org, the actor tells reporters that he won't go to the bathroom until everyone in the world has access to clean water and sanitation. Matt, who's the co-founder of the website, says, "Anybody have any idea what invention has saved more lives than any other in the history of humankind? The toilet. What's even more shocking is the catastrophic worldwide lack of clean water and sanitation. 780 million people -- that's twice the population of the United States -- lack access to clean water. 2.5 billion people lack access to a toilet or basic sanitation. I mean, more people have cellphones than have toilets."

Matt wants everyone to help. He says, "Join me. Say no to toilets. Say yes to clean water for all."

For just $25 a day, Matt says, one person can get clean water for life. To find how you can help, visit StrikeWithMe.org.