Faceslacker
A friend who only exists on Facebook. They post on your wall like they're your best friend, but if you walk by them in the hall, they ignore you completely.
They added me on Facebook, but I've never seen them in real life.
They posted on my wall, but when I said hi in the hallway, they ignored me.
They said, 'You're the best!' on my wall, but when I walked by them, they didn't even look at me.