Why So Serious

Why So Serious is an achievement in Halo: The Master Chief Collection. It is unlocked by viewing the smiling face in the classic multiplayer map Coagulation.

The face can be found on one of the three rocks outside of Red Base. The achievement is worth 5 Gamerscore.

Trivia
The name of the achievement is a reference to the 2008 film The Dark Knight, which spawned a meme of the same name.