Maybe we can get some UK folks out here to chime in on where the term “the Loo” came from...
Anyone UK people on the board, please jump in here....
It’s my understanding that it came from the era when lodging facilities had one “bathroom” for the entire facility, not one per room as is normally the current practice.
That room was always “Room 100”.
The “100” then took a short trip to become “loo”.