Faceback
To back out of or delete something you posted on Facebook because you suddenly realized how stupid you looked. It's like when you say something dumb and then instantly wish you could erase it.
I posted 'I hate my life' and then realized I actually kinda liked my life.
I commented 'This is the worst movie ever' and then watched it again and loved it.
I sent a message saying 'I'm gonna kill you' and then remembered I was actually friends with the person.