It’s not really black humor to me, it just talks about people who go to war and what can happen. Men need to defend what’s right and good, and they can die doing that. The song is just a metaphor.
I don’t know why everyone defaults to the “King and country” argument as to why men go to war, all the decent men I knew would go to protect their families. There’s a spectrum of reasons obviously.
I’d still “jump” for the right reasons, not because I’m getting ordered. Men don’t really do those types of things for enjoyment. In many ways fighting against things here is a thankless task.
But to keep to the music theme and men singing in harmony, here’s an easier song to listen to. Stan Rogers wrote his own Sea Shanty so he could sing the lead after hanging around the Irish fisherman(if I recall correctly)