Slang allows people who are in “in the know” to break the code and presents a linguistic barrier for unwanted outsiders
Unfortunately, I do this a lot with online players whenever playing Guts and Black Powder. We don't even know each other but once you play the game long enough you all kinda know that words and stuff. So you could say like "Lets do Vard" and to new people that sounds like we taking drugs but its really just us choosing the map "Vardøhus Fortress". Small things like that.