When you check out your facebook but keep your chat status changed to offline. That way no one knows you are online for hours facebook creeping on other people. You avoid being named that guy thats always on ie facebook whore. You also avoid being forced to chat with people you would rather not. Is easily spotted if you post or comment but do not appear as active in chat.
The third time after an annoying new facebook friend began chatting with me as soon I got on, I began silent creeping instead.