Yes!
When I used to work for a larger company, the younger crowd (men, since it's engineering) used to occasionally have discussions on the unspoken rules of using stalls & urinals.
Which one to go to, which to choose... and most important, who-uses-which.
LOL on the shoe thing.
I usually sway my feet to one side if somebody adjacents-me.
The fake-cough when somebody enters is my fave unspoken communication. All must understand the meaning.
It announces "I'm in mid-dump. You can piss & leave, but you shall not stay for your own dump. Get the **** out."