This phrase is preceded by your name and is used primarily in online chats where you are capable of logging in/out. It is used as a response to an absolutely idiotic comment, where you feel the need to log off on this person. Equivalent of slamming the door in someone's face, the ellipsis ("..."), or actually logging off on them.

Other variations include, but are not limited to:
- ____ has logged off.
- ____ is no longer able to chat.
- ____ has signed out.

to tell someone to calm down and relax.