When updating your facebook status with something aimed at one specific person without actually naming them. Or having facebook status with hidden meaning. The person in question knows that that this status is about them. Resulting in a response on facebook aimed at them. A slanging match or 'code-off' occurs.
'Dude what is her facebook status all about, it's obviously about me?'
'I have no idea, why don't ya write one back and have a code-off'