POSTAL Brain Damaged: All Secrets & Poster Locations in the Eleventh Level (Fluffy Friends Festival O’ Fun)

You will be at the beginning of the level.
There is a line of civilians at a blue ticket booth.
Jump into the window and the poster should be in here.

Make your way throughout the tents until you see a pile of boxes as shown here.
Walk through the path in the boxes and you should see a Penetrator bow.

When you see the huge Expo building, go to the left side of it.
You will fight some enemies until you see this pile of boxes.
Walk through the boxes to find a poster of the T-8000 enemy on the wall.

In the same area where you find those boxes near the T-8000 poster, there will be a yellowish manhole opening. Jump down to the sewer area where you will fight groups of enemies.
Proceed through the area until you climb out into the public washroom area where you can piss on a power circuit to free yourself.
Before you exit out the bathroom, go near the wall on the right.
You can walk through this wall here.
Once you cross over to the other washroom, there will be a Health Pipe here as well as the button that unlocks the door.

Make your way back to the Expo building, this time go to the ground floor parking lot.
Be warned that there will be two car enemies and a RPG table waiting for you.
The poster will be right here on the wall.

Assuming you gained entry into the Expo building, there will be numerous panels in this building.
Try looking for this panel that advertises Blood West, a game also made by HyperStrange.
The poster will be on the wall.

There is a downstairs restroom area in the Expo building.
Eventually you will make it into a long hallway with potted plants and doors.
Keep an eye out for a sign that has the number 3 in Roman numerical form as shown.
Here you will see the unfortunate Postal game that never existed.
Fun fact: you can piss on it then flush it down the toilet.

Eventually you’ll be required to use launch pads to get up into the rafters.
You will need to go through pipes that are littered with Crawlers.
You will drop down into a room with items kept in glass cases and seemingly a lone Illuminati man.
Deal with the situation as you see fit, you will notice three metal doors.
The leftmost door is breakable, you will unlock the secret and find the last poster after you kick it down.
HUGE SHOUTOUT TO Paya for mentioning this secret!