Obeek
When two people are so tight they can read each other's minds and still argue about the same stupid thing.
My buddy and I are Obeek. We know what each other is thinking, but we still fight about who's the better video game player.
They're Obeek. They even know each other's secrets, but they still argue about who's the bigger loser.
If you're Obeek with someone, you know their mom's phone password.