What made me know that Army also stood for a person is because during one interview where they were sitting at a table the question was asked who would they want to be left on earth with(something like that, I'll try to find the video) and Jk said Army or Army's love, then Jimin said to Rm "I'm Army". Now up to that point Jk and Jm had been doing a lot of fan service which I thought was real at one point until I saw video that showed me that it wasn't when Jimin said to Jk "I told you to only do that when the cameras are on" with a serious face and tone. I started to look at their "ship" in a different way. To me, their ship was Jimin acting in place of Jk's girlfriend, like what already happened in real life between Jk and the girlfriend or a message Jk was giving to her because they hadn't communicated, same thing with the vlives.
Jk was my bias and my niece swore by jikook and I was like hmmmm, ok. Then not long afterwards I was like nahhh everything you see they are letting you see and it just don't make sense so it got me to looking further. I love a good mystery and especially solving them. Everything isn't always what it seems.
Here is an example of inserting the name of his girlfriend for <ARMY> and what you would get. In this case, men talking dirty.
Of course the others know who ARMY is code for other than their fans. Look at all of their expressions, tones and inflections. They think no one will ever catch on to their inside joke. They have lots of em ALL THE TIME.
Look at 10:45-11:25