Halo: The Master Chief Collection - Halo 2 - Why So Serious - Halo 2: View the smiling face in the classic multiplayer map Coagulation. This achievement is fairly easy to unlock.
On the map Coagulation, as soon as you spawn find the red base. Head to where the are three large boulders. On one of the boulders there is a face that you need to look at.
Look at it and your achievement should pop! Enjoy!