Tansy

“I took a wrong turn on the way to the bathroom and found myself in a beautifully proportioned room I had never seen before, containing a really rather magnificent collection of chamberpots. When I went back to investigate more closely, I discovered that the room had vanished. But I must keep an eye out for it. Possibly it is only accessible at five thirty in the morning. Or it may only appear at the quarter moon - or when the seeker has an exceptionally full bladder.”
― J.K. Rowling, Harry Potter and the Goblet of Fire