Long time ago i shared a trick on facebook using pages tabs, the trick will get you sign out dynamically once you opened the link . check it here
After the several loopholes in facebook notes (img tag), unknown users start using such code in note bad, editing the tag img source to the link that will force your account to log off.
<img class="UIShareStage_Image img" src="https://www.facebook.com/n/?home.php&medium=email&mid=a4986bbG5af4d7fd6e6dG0G114G12e9d8e3"/></img>
For sure the trick has been reported hundreds of times by users to facebook, it will be patched soon .