In their underwear (poop)

… and poop in their underwear. In this reality, toilets never got invented creating a problem with waste on the streets and to bypass this, the royal family at the time made it a legal requirement to shit and piss in your underwear. The problem was largely solved and laws were changed or reworked to make this work better as people would often shit or piss in their underwear then later empty it in the streets, this defeated the purpose. Instead of trying to find a new solution, the royal family pushed through and stated that shit, at least, did not have any place on the streets and should be instead emptied in the house.

In the modern day, these rules still apply with a culture of only wearing underwear came about and technology allowing for more stretchy underwear to fit all the shit in a day. The shit is emptied in a family pile in a small room, this pile is treated like the families most treasured thing as it's size can be a thing to show off, despite the smell. people evolved to have ass cheeks resistant to rashes. A person will own many drawers filled with underwear as it is expected that at the end of the day you will throw your messy underwear on the family pile either emptied or with the shit still in. Underwear and shit is seen as the family property, therefore taking your sisters underwear or grabbing shit from her underwear while being worn are acceptable, you may do these things to another person if they allow it.

Women don't wear bra's as they were never invented and currently there are many changes being made to laws and such, so this is not all necessarily true by the time you wake up.

[Author note: I've been very unsure as to if I should publish anything because I feel like everything I write is too long or doesn't make sense, but I feel like I should publish something even if only to get feedback, feel free to continue from any point or change anything, just mention the changes.]