|Some of us never take them off, not even in the shower.|
After failing to appear at a press conference at the Cannes Film Festival for his upcoming film, "The Beaver", Gibson is depicted here wearing a Scapular, or a religious garment that consists of two brown pieces of wool attached to a string worn around the neck. From the looks of it, this is a really cheap one he's worn for ages, it's tied around his neck, the brown colored tag of fabric hanging down. It has an image of St. Simon Stock or St. Micheal the Archangel defeating the Devil, with an inscription which reads, "Whoever wears this scapular shalt not suffer eternal fire". It's a promise associated with the scapular that whoever wears it piously and follows its promises will be taken to heaven.
Photo from the Daily Fail.
Edited for clairity.