1) The term used when one is in the same room with a person/people who have a mobile subscription to your Facebook status and you update in front of them, causing them to dive for their phones, only to read something they already knew.
2) Any time Facebook commits an error.
3) When someone enters the same status you were going to use before you.
My phone just went off, it better not be you updating your Facebook! Oh crap, it is you. I got FACE-BAGGED!
I updated my status on my phone like an hour ago, you never got it?! Man, I got FACE-BAGGED!
Oh this is so cool, I gotta put this as my status. What?! You already did!!? I got FACE-BAGGED.