POSTAL Brain Damaged: All Secrets & Poster Locations in the Seventh Level (Definitions of Insanity)

This guide is to help those who want to get the secrets and posters on the seventh level, Definitions of Insanity.
It’s complete!!!

Poster #1: Lost Clown

You will start off in the courtyard of the sanitarium.
There will be stairs leading up to this building that cannot be entered.
Two Lobotmized Creeps will be waiting in ambush.
Take care of them and the poster should be on the left wall.

Poster #2: Nurse Joy

I will assume you pissed on all the circuits, entered another garden area with branches, proceeded to find a Red Key and flip a lever to access the Red Door.
There will be a poster in the area you just entered with a few zombies, Lobotomized Creeps, and a Farty Pants.

Secret #1: Bat Wall

Soon you will enter an area with two grapple rings, be prepared for a fight once you use the blue key then activate the Hot Sauce fountain.
Once you dealt with the enemies and pissed on the Ferris Wheel, you’ll go into it and press the button to go to the rooftop area.
Go into the center room of the rooftop that has this bat on the wall.

Interact with it and a room will open inside the wall opposite this bat.
You will be awarded with a Double Akimbo powerup.

Poster #3: Definitions of Insanity

Once you retrieved the yellow key, you will be able to unlock the yellow gate.
Across from you, there will be two small raptors that have machine guns.
Deal with them from afar because they can melt you quick.
Once you’re done, turn around and you should see this poster.

Secret #2: Minotaur Garden

Jump down into the next area.
There will be a tuba man guarding the wheel that activates the Hot Sauce fountain.
You will notice that there is an opening in the hedges next to the wheel.

Enter it and you should see a dead minotaur corpse in the floor and some ammo.

Secret #3: Ferris Wheel

Remember that Ferris Wheel you took to get up to the rooftops?
Loop all the way back to the area to find another Ferris Wheel cage with a button.
Press the button to activate the portal then enter it for the secret.
BUT I highly recommend you drink the Hot Sauce Fountain before entering it for the next secret.

Secret #4 / Poster #4: Lizard-Dude

Once you return back to the rooftop area after drinking Hot Sauce, go back to the dropoff point.
Look to the right and you should see a flammable plant, pee on it.

After you have successfully burned the plant, you want to slidejump onto that area.
You will unlock the secret and the poster will be there too.

Thanks itchy ivan for helping!

Thanks to AZRA3L The Eternal for his great guide, all credit goes to his effort. you can also read the original guide from Steam Community. enjoy the game.