This is a very easy achievement and an Easter Egg. Load up Act 2, Chapter 1, "The Prodigal Son" on any difficulty. As soon as you gain control of JD, move forward until you come across a square shaped hut to your right. You'll see the door you're supposed to go through to meet Marcus to your left and a smaller gate to the right.
Go to that gate on your right and press
when prompted. The achievement will pop right at the beginning of the cutscene that follows.