This guide is to hopefully help those find all the secrets and posters in the fifth level, Black Friday Showdown.
Locations of All Secrets and Posters
Poster #1: Black Friday Showdown
At the beginning of the level, just continue to progress through the level until you reach this area.
Make your way towards the bottom of this room where a tuba man, crawling dolls, and a cage monster await you.
The poster should be on the wall of the center pillar.
Secret #1: Double Akimbo
Next, you should play the level as usual until you reach this junkyard area.
Make sure you have a rocket launcher or a Burger Boi that you can grapple onto.
Your goal is to rocket launch / grapple over this wall of containers.
You should find a Double Akimbo powerup here.
Secret #2: Back of Wallmarket
Continue forward to use the Red Key to get to the Wallmarket area.
You will see a crowd of civilians and veterans, but do not enter the store yet.
Go around the blue building to get this secret.
Secret #3: HyperStock Wall
Fair warning, once you enter the store, you will not be able to go back to get any missing poster or secrets. So go get that poster and two secrets before you enter.
Once you enter the store, you will be closed in it and there will be a piss toll.
Instead, you should turn around to find a wall labeled with HyperStock.
Walk through this wall to find a Double Akimbo and Portable Armor.
Poster #2: Karen: The Manager Slayer
In the Wallmarket boss area, go to the bottom center area with all the rubble and desert sand.
The poster will be on one of the walls. Also good luck with fighting her.