Unlimited AP
Enter combat, walk up to one of the characters, put the only ammunition for your gun (not the weapon), in your hand. And take a shot at your opponent. He should say something similar to "Did yo mama' teach you that move?" to confirm correct code entry.
Better armor class (demo version)
When starting, put on your armor in the inventory. Click to drop the armor that is on your character. Leave the inventory screen and pick up the armor and put it on again. Your armor class should be twice as much as it was before.
Better armor class
Note: This trick requires v1.0 of the game. Get a bag and some armor. Equip the armor, then enter the bag. Drop the armor off of your character, then pick it up. Repeat to build your armor class.