Tweeter 2: "Really? When did he do that?
Tweeter 1: "This morning. He made a tweet."
Tweeter 2: "He came out on Twitter? That's So Raven."
The phrase means you're so uncool or lame or copyrighted.
Stephanie: I don't know i didn't do anything last night either way
Sarah (checks to see if they had homework): Dude Stephanie we did have homework and it's worth 20% of our grade
Stephanie: OH SNAP!
Sarah: Dude that's so raven (shakes her head)