One of the central facts in any military professional's life is that you really must be two people. There is the You that your family and friends know, the you that is free to bum around the pad in jeans and slippers unshaven, to do as much or as little as you please with every day. The other You is the Officer, who presents at all times a clean appearance, who takes responsibility for all their actions and behaves properly within their station.
This division creates some problems, mainly relating to how you address a superior in a social setting. A Mister or Misses Last Name is always safe, but christ, just passing by a fellow 4/C on the street I'm not gonna go "Hey there, Mr. Middy. How is it hanging?" For most of these kids, it'd be perfectly acceptable to know each other by last names only until the end of time. I think that as the year presses on and we all become much more familiar with protocol and whatnot, they'll ease up, but for now I've decided to learn everyone's first names and use those in random encounters. Hopefully that will help everyone to relax, although not so much that we start that nonsense in uniform. That would be a Bad Thing.