Via Clara, if you attempt to do anything against Facebook, such as attempt to circumnavigate paywalls:

javascript:window.location="https://m.facebook.com/l.php?u="+encodeURIComponent(window.location.href);

You’ll get this in your browser console:

 .d8888b.  888                       888    
d88P  Y88b 888                       888    
Y88b.      888                       888    This is a browser feature intended for 
 "Y888b.   888888  .d88b.  88888b.   888    developers. If someone told you to copy 
    "Y88b. 888    d88""88b 888 "88b  888    and paste something here to enable a 
      "888 888    888  888 888  888  Y8P    Facebook feature or "hack" someone's 
Y88b  d88P Y88b.  Y88..88P 888 d88P         account, it is a scam and will give them 
 "Y8888P"   "Y888  "Y88P"  88888P"   888    access to your Facebook account.
                           888              
                           888              
                           888

Interesting.