Facebook Hampster
The Facebook Hamster is the friend who's always online but never around. They watch your life like it's a show, but when you try to talk to them, they're too busy living their own life and ignoring you.
You message them about a movie. They reply with a link to their own movie.
You post a new haircut. They like it. Then they vanish.
You tag them in a post. They like it. Then they don’t reply for a week.