In the closet room inside the Warden's Office Area on the middle left of the 6th floors, there will be a Golden Toilet. The Warden's Office is marked on the in game map and can viewed by selecting
. Simply get to this toilet by either using a Red Key, Red Key Copy, or a Grappling Hook (to circumvent the Red Key Doors) and flush any random item down the toilet. There is a lootable desk nearby if you don't have any garbage items on hand. Once you flush 1 item down the toilet the achievement will unlock immediately!