This is earned for finding optional collectible #5. If missed on the first run, you can "Play Episodes" and select specific parts of the Episode in order to find the missing optional photos through collectibles mode
. The following collectible is described and can be seen in the video below at 5:07:
You will return to the campsite at night during a party. Talk to Cassidy and get the tattoo. Afterwards, do not follow Cassidy, instead talk to Ingrid. Ingrid will tell you to look at the stuff at her camp if you want any of it. Go to her tent and pick up the collectible.
Getting all 6 collectibles in this episode will also reward you with the following: