Even if you have the most stringent security Facebook will allow (ha!), a judge recently ruled that your Facebook friends can legally show cops your profile, and you can go to jail for incriminating evidence.
A man named Melvin Colon (Facebook user "Mellymel Balla") was recently arrested in New York on racketeering charges, largely through the cooperation of his Facebook friend who showed police some suspect Facebook posts and pictures. US District Judge William Pauley III ruled that the suspect had no 4th Amendment protection (prohibiting unreasonable searches and seizures) via his online profile. According to the ruling, Colon's "legitimate expectation of privacy ended when he disseminated posts to his 'friends' because those 'friends' were free to use the information however they wanted—including sharing it with the Government."
Of course, all of this kind of falls under the "duh" category. Online etiquette tip: if you're involved in any criminal activity, think twice about posting pictures and updates of your behavior on your Facebook timeline. After all, you never know who's watching...[Gizmodo]