Slang in the military can be coarse, profane, ignoble, cynical, irreverent, rowdy, provocative, bawdy, amoral, and even savage. Yes, it is all these things, but soldiers embrace it, especially in wartime, in all its euphemistic and dysphemistic glory, because it is a quick and easy way to communicate, fosters self-confidence, promotes companionability and even intimacy, promises allegiance, grants exclusivity, pushes against the restraints of military discipline, exudes toughness, and provides pleasure.
Certain subjects readily lend themselves to slang use: death, disease, unpleasant actions, trench life, food, tobacco, allies, enemies, second lieutenants, chaplains, infantrymen, men back home, bayonets, hand grenades, machine guns, gas masks, shellfire, fear, prostitutes, and language.