Quiet cars on Metro North

Imagine my stunned delight/horror this evening when I realized my friend and I were the only 2 in the entire train car TALKING. I just thought it was some kind of absurd luck to finally be free of the Idiot Yammering Public...but he soon advised me to "keep it at the level we're talking now" because we were in some Quiet Car. I remain unclear on whether it was actually designated as such or if this was just some natural commuter-born code of conduct. I DO know I was mortified at the idea that I was the one irritating OTHERS, thus quickly stifled our conversation and immersed myself in the NY Post, followed by "Look, everyone, I'M reading" The Economist. I also know EVERY single train or bus in the nation should adopt such a policy, or at least shove the infuriating cell phone users and obnoxious high-decibal finance co-workers excitedly recounting their arduous trading day into one tightly-sealed car. I rode for almost 90 minutes in almost absolute silence...the perfect soothing commute. Thank you!! *PS...bonus points for being allowed to get liquored up.