1) Start Episode One of Chapter Five.
2) Pick up a DMR Rifle or any other scoped weapon.
3) Kill the first group of foes that come your way.
4) Head up the ramp nearby.
5) Jump onto the ledge behind the energy barricades.
6) Look down into the lava.
7) Aim into the scope of your weapon.
8) Look around and you will see a small box in between a crack in a few rocks.
9) Shoot it and you will hear a sound.
10) The achievement will immediately pop up and throughout the mission you will hear some quotes from "Red Vs Blue".

Here is a video tutorial which will help you locate the box quicker: