E E E Achievement in Halo: The Master Chief Collection

This Easter Egg can be found in the mission, Metropolis.

After emerging from the large, winding highway tunnel and fighting past a large unit of Covenant forces (including a Wraith) inside a gassy valley, you will eventually return to the city streets of New Mombasa. Here, your main objective tasks you with progressing towards the building on the other end of the street to regroup with your Marines.

Before doing that however, take a sharp left the side-street that branches off the main street. Here, continue moving to the forward down the street and in the far left corner, you will find a terminal-like console that flickers two different messages. Simply look at these signs in Remastered Mode for about ten seconds and the achievement is yours.