My roommate goes off in the evenings to spend time with two guys from his home town. The three of them deployed together before almost five years ago, but can happily spend an evening talking about things that have nothing to do with the Army or the current deployment.
He says the alternative to talking with each other is talking about each other. The main topics of conversation on deployment are home, complaints and gossip. And gossip quickly takes center stage. When people see each other as much as we do, we know each others foibles and weaknesses to a degree that is only possible in families in civilian life.
At this point, it's clear that simply mentioning some soldier's name will lead a group at dinner to groan, laugh or shake their heads depending on the person. And because it is such a close group, the comments circulate quickly. One one field exercise, I told my vehicle crew that I would not allow anyone to talk on cell phones inside the vehicle when we were waiting for instructions. It was raining off and on that day. The rest of the crew knew I made up the rule for only one soldier in the vehicle who would complain to his mother/girlfriend/(dog) at every halt if allowed. I heard comments with sly smile for a week after from soldiers who heard the rule I had made and were delighted that particular soldier was not allowed to drone on and make the rest of the crew suffer.
For those who would think gossip is optional, being part of the gossip also identifies one as part of an informal group. A group that when gossip when you are present considers you an outsider. If you hear "She's a f#$king idiot" when you are eating with five other soldiers, they are letting you in on their group opinion. To be outside the gossip is to be outside every informal network.
For those who would like to read the definitive essay on this subject cliques and who is on and out, the essay "The Inner Ring" in CS Lewis' book "The Weight of Glory" is wonderful on this subject.