You'll need to turn on cheats in your game of Postal 2. To do this, pause the game and open the cheats menu located at the top. If you haven't beaten the game (don't know why you'd be reading this if you haven't) just hit the ~ key and type "sissy" into the console
Now that you have cheats, you'll need to enter a command that isn't toggleable through the games built-in cheat menu. In the console, type "ifeelfree" this will grant you Noclip and Godmode. To disable the command type "ifeelfree" again in console to disable it.

You might think that with Noclip active it would be as simple as flying though the load zone, but this is not the case. Flying through the load zone will simply show you what's on the other side. This is honestly neat as it allows us to explore more past load zones and see the pieces that are creating the illusion of a continuous map.
To get though a load zone, you need to Noclip yourself right on the line where you would normally begin loading to the next zone. You'll then need to turn Noclip off and continue through the zone normally.
Congrats, you've now made it to meat world on Monday.
If you try to noclip past the load barrier and untoggle it past the load zone line, your game will crash immediately in most cases.

This technique can be used on any load zone (from what I've seen at least), even the larger ones like the rock wall that blocks you from getting to the clinic.

Breaking into one blocked part of the map can also help you get around, as some areas don't have barriers to others because you were never supposed to get there that early. We can see this clearly with the Napalm Factory Exterior. It's blocked from the tracks, but isn't in the Clinic Area.

You are also completely impenetrable to all damage while using the "ifeelfree" command.

Since this whole guide is about console commands anyway, I thought I would include something else that might make goofing off in Postal 2 more fun. The Super Grenade Launcher is a weapon that was made for the "A Week In Paradise" fan mod before the grenade launcher that we can see in game today.

It is a retextured rocket launcher that is much greener. It fires a grenade normally with left click, and charges up a special attack that shoots several grenades when you hold down on right click.

To get this weapon in game, reopen the console and type "IWant AWPStuff.AWPGrenadeLauncherWeapon"

This will add the weapon to your game, but you'll need to use the "PacknHeat" cheat to get it.

Alt-Fire:

Congrats, you now can blast enemies while flying around outside meatworld with a Super Grenade Launcher on Monday. I hope you liked this guide, please give me steam points my wife and children are starving.