At the end of Gain New Allies, you will have to head back to your house because it is past your bed time. Note that even if you take your time, your parents will come and force you back there. Go to bed and you'll be awakened by some underpants-stealing gnomes. You'll be thrown into a battle with them, which is impossible to lose since they will only do 1-2 points of damage per attack.
However, after that initial battle, they will shrink your character and the real battle will begin. Pretty much all of their attacks come with debuffs, so you have to make sure you try and guard to minimize damage and not get stuck with them.
After winning the battle, chase the gnomes through the hole in the wall and you'll be in another dungeon-like area. Be careful of the mouse trap past the first wall and climb the walls to the top area. Move to the left and you should see a giant rat underneath. Destroy the pipe to make a puddle appear, use Sneaky Squeaker to lure it to the puddle and then shoot the frayed wire to electrocute it, sending it running into the mouse trap.
Move into the vent and you'll see a short scene with your parents, after which you exit the opposite end. Climb the wire and go left, avoiding the electricity, for a chest, then shoot the screw above you on the right side to create a ramp for you to continue.
There will be one rat stuck in the wall, which you can kill by climbing the wire, shooting down the foam insulation and using a fart to make it explode once it catches on fire. If you stay up top, break the wall and hit the pipe to kill another rat, leaving you to only have to battle a single rat. Continue after the rats to a spot you can leave and appear on your parents' dresser.
| When you appear on your parents' dresser, you will see them having sex. If you stay still for 60 seconds, you will get the Perverted achievement/trophy. |
Go to the right on the dresser to confront some gnomes, then defeat them in battle. Continue further and go down the rope, where you'll eventually come to fight the Underpants Warlock. Other than him having high armor, the fight isn't anything special and should be pretty simple. Make sure you watch out for the very quick QTE-move called Hanging Low. This quest is now finished.
| As with the Alien Probe, your newly-acquired Gnome Dust allows you to access areas you couldn't otherwise. |
