Touching Cloth Tetrus

I'd just got off the tube train at Victoria ready to get the bus to Edinburgh festival but my bowels were bursting.
I dived for the nearest cafe which turned out to be packed as they usually are in London and asked the waitress where the toilet was. Without pausing I bolted up the stairs. She seemed to saying something about a 'code,' but so engaged was I in the pursuit of the bog that it went in one ear and out the other.
There were two doors: A woman's public toilet on the right, open, and a men's with a code lock on it. That seemed odd but I still bashed into it, assuming it was open, only to rebound back into the cafe, where coffee sippers gazed up at me from their mugs. What's this?! A Code? When women seem to be walking freely in and out of their toilet? Is this some sort of patriarchal test of logic whilst you clench your rectum, or a twisted form of touching cloth Tetras?
This needed investigating. I asked the waitress about this and she gave me the rolled-eyed look before repeating the code to me. I didn't think about it too much whilst I had to the glorious chance to relieve myself, I only felt sorry when I left, walked down the corridor and a bloke passed me on his way to the most inconvenient moment of puzzlement.