This is a written guide from the easter egg I saw in this video by DannyCrew- https://www.youtube.com/watch?v=kuzmRFIkVLg

Step 1: Turn on Power

Step 2: Shoot the 3 radios (there will be a teddy bear next to each one)
Location 1 - Under the desk on the top floor of the power switch building
Location 2 - To the side of the stairs leading up to Pack-a-Punch
Location 3 - On top of the tank in near Speed Cola

Step 3: Pick up the film reels
Location 1 - To the right of the Juggernog machine up on a ledge by the red crate
Location 2 - On top of some gridded crates by the Widow's Wine machine
Location 3 - Behind the outcove of where the Double Tap 2.0 machine is leaning on a red crate and covered by a wooden pallet.

Step 4: In the Double Tap 2.0 area, there should now be a red circle on the floor by the drop down from Widow's Wine. Place the film reels on the circle and then interact with them again to start a soul box event. Zombies will spawn non stop until the soul box is filled so get ready to camp for a bit.

Step 5: Once the soul box is filled, pick up the audio reel left behind

Step 6: Bring the audio reel up to the 1st radio location and play the audio reel.

Congrats! Some dialog will now play and you will be awarded a Perkaholic