Halo: The Master Chief Collection - Halo 2 - I Like Crazy - Halo 2: Collect the Rampant Cortana toy in High Charity. This achievement is fairly easy to unlock.
On the mission High Charity, when you go through a door and there is a bend to the right and gravemind is talking to you.
Run to the other side and climb up the rocks where the toy is located.
Run over and it up and your achievement should pop! Enjoy!