Mod goes in ...\TheKillingAntidote\Content\Paks\~mods
Jodi's Secret Collection.
A lot of panties (100+). Really only 2 types but have several different design prints on them. Many have option to change color values.
They are not immediately available in wardrobe. Its clothing tab is the default name that majority of workshop mods used (which makes the tab list longer
).
They are unlocked from one of the vending machines in the story that sell clothes and sometimes as a clothes box for underwear. There's even Halloween specific prints you can get from Nightmare Castle challenge. They appear as a box you find like normal there.
Clothes box grind is harder, mainly because the game will generate boxes for base game clothes you already have.
Grind money from the challenge room on floor 4 to help buy everything (except Halloween themed stuff).
This mod is the only one that did the "play game to get cosmetics" route compared to all others that just give you the stuff, making it really unique in that regard and adding a bit more replay-ability to the game. The only negative thing about it is that there's only 2 panty models for all the prints.