Guys and washroom...

So there is an unwritten rule that when a guy goes to the washroom and there are three urinals, you take one of the end ones so that the next guy coming in can have the other end one and you have a buffer zone between each of you. I don't know why exactly that is, whether for peeking reasons, for spraying reasons, or for talking reasons. Whatever the reason, that is the unwritten rule and I abide by it.
So I'm in the washroom today and while the above rule wasn't broken, something just as bad happened. I was doing my business at the urinal when a co-worker came in. He said hi in passing and proceeded to a stall. Being polite I said hi back not expecting a conversation to start! You can almost manage a urinal conversation (although it really shouldn't happen), but a urinal and a stall conversation? Never! You just can't do that with the other "noises" that may happen when you are in a stall - and they happened today! People, there are doors on stalls for a reason. Please keep all conversations to yourself and whatever noises you create. We'll catch up outside the washroom, thanks.