SOME celebrities don't know when to keep their traps shut - like Charlie Sheen and Rosie O'Donnell, who are throwing their weight behind the twisted theory that the United States government was behind the 9/11 terror attacks.

Page Six has learned that Sheen, the hooker-loving Hollywood hunk, has agreed to narrate a new version of the loopy YouTube documentary "Loose Change," which claims that a corrupt faction within the federal government orchestrated the mass murder at the World Trade Center.

Sources say Sheen - whose father, Martin Sheen, has been arrested 63 times protesting on behalf of various leftist causes - is in talks with Dallas Mavericks owner Mark Cuban's Magnolia Pictures to distribute "Loose Change." Sheen has called for a new independent probe of the attack, telling Alex Jones' radio show: "It seems to me like 19 amateurs with box cutters taking over four commercial airliners and hitting 75 percent of their targets, that feels like a conspiracy theory. It raises a lot of questions."