http://www.urlesque.com/2010/11/11/facebook-super-logoff/
Internet researcher danah boyd says that kids are using the super-logoff because they don't want people finding them or friends posting on their walls when they can't be around to respond or take down anything they don't like. A similar trick is the "white wall," where a Facebooker periodically deletes all the comments and posts on his or her wall, making sure only the newest and freshest posts are visible. Combining the super-logoff and the white wall is much more hardcore and much easier to understand than tweaking all those complex Facebook privacy settings.
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