Millionaire actor Ben Affleck will be trading in his riches for rags to raise awareness of extreme poverty around the globe.
The Academy Award winner has vowed to live on 98p ($1.50) a day, for five days, in an attempt to highlight the plight of the world's poorest people.
He joins actor Jonah Hill and singer Josh Groban in the Live Below the Line Challenge.
The 40-year-old father-of-three announced his decision to get involved with the cause on Twitter and urged fans to show their support.
"1.4 billion people live on less than $1.50/day. I'm joining Live #BelowTheLine on behalf of @easterncongo. Will you?" he told his 560,000 followers.
The Argo director is undertaking the campaign on behalf of the Eastern Congo Initiative, the charity he set up in 2010 to help displaced people in the wartorn African region.
Affleck, who is married to actress Jennifer Garner, said he founded the charity to set an example to his daughters and "do more with my life than just make movies and try to make money".
Organisers recommend that those getting involved should spend their $7.50 (£4.90) allowance on food at the start of the week.
The rules stipulate that participants are not allowed to eat food from their kitchen cupboards or accept food donated from friends and family, but they are allowed to drink tap water.
"We recommend doing research and creating a shopping list, sticking to generic staples such as pasta, lentils, rice, bread, vegetables, potatoes and oats," the website advises.