Sorry, Little Monsters, Lady Gaga is signing off Facebook and Twitter for charity. Starting Tuesday (World AIDS Day), she and a host of other celebrities—including Justin Timberlake, Usher, Elijah Wood, Jennifer Hudson, Ryan Seacrest, Kim and Khloe Kardashian, and Serena Williams—will shut down their social-networking pages until Alicia Keys’ charity raises $1 million. Each of the stars has filmed a "last tweet and testament” for the campaign, called Digital Life Sacrifice, which supports "Keep a Child Alive," a charity funding families affected by HIV/AIDS in Africa and India. Of all the participants, Gaga has the largest online presence, with 24 million fans on Facebook, and more than seven million Twitter followers. "It's so important to shock you to the point of waking up," Keys said. "It's not that people don't care or it's not that people don't want to do something, it's that they never thought of it quite like that."