Public and Private

After many discussions of the separation of the public and the private in classes this year, today I am forced to wonder whether the "average" American even conceives of a difference between the two. Case in point:
This morning I am at the Caribou, ready to embark on the "journey of triage-reading" for classes this week. The usual suspects are here - my veterinary school friend who is here as often as I am, the German-born Conservative Republican couple who are always engaged in some kind of Rightist conversation with those around them, the Caribou worker who drives me to feel the need to drink, and, my personal favorite, the older gentleman who invariably feels the need to come to a very public coffee shop to have very private conversations with his family on Skype. Today, however, was a brand new day in "information sharing" at the coffee shop for this man - today he proceeded to have conversations that were so loud that he alienated 3 couples sitting nearby (including said German couple) to the point that they left the shop. My veterinarian friend, unfortunately, was at the table next to him and her earplugs (yes sometimes they are necessary) were unable to perform adequate duty today.
My personal favorite moment was when he told someone on the other end of his "conversation" that he wanted to show them something...yes, the infamous words. He then got up at his table and proceeded to detail the parts of his body, as he turned around, giving the other person a "show" on Skype of his newly acquired 40 pound thinner body....we were informed that he used to be 220 something and is now down to 186, and that he was, and I quote, "trying to be a good boy and eat better and be better." Further conversations, with children I assume, resulted in him making kissing sounds at his screen and blowing kisses to those on the opposite end of Skype.
Now, all of this may sound perfectly fine to some, but caused a lot of discomfort in a very public setting. Aren't these types of conversations generally private? Why would you come to a coffee shop to have this type of exchange? Somehow, I can't imagine myself getting up in the middle of a public space to declare my new "body" to someone on the other end of a video-conversation.
My veterinarian friend commented, "When he said 'I want to show you something' I was just hoping that his pants were staying on behind me." I, myself, was afraid to look in that direction after hearing him say this over and over again.....inevitably showing people his body over and over again in multiple "conversations."
So, I ask, what is public and what is private?