I'm sitting in the Hofbräuhaus in Munich and just noticed that the signs for the bathroom are a symbol of a man and woman with a "00".
Why is this the case?
According to the legend this tradition was started by hotels in the 19th century. Unlike today there was a single bathroom for a whole floor. This room was at the beginning of the hallway and not a real guest room. Hoteliers therefore used the room number "00".
Other common explanations include the shape of an opened toilet seat but as far as I know that question has not been finally settled yet. The hotel explanation seems like the most likely one.
The German children’s show die Sendung mit der Maus once talked about that. Their explanation was:
Weil da 0 arbeiten und 0 wohnen.
Because 0 work there and 0 live there.
I am aware that the explanation is a little sketchy but it was broadcasted on national TV so …
It's an outhouse
Flushing toilets are marked WC
Non flushing toilets like outhouses, porta pottys and shitholes in general are marked as 00