Every line of work has its own secret language. Pilots, nurses, actors, filmmakers, and sailors all use words and signals that mean something very specific to insiders. If you’re an outsider overhearing them, you probably wonder, "What the heck is going on?" Some of these terms are technical, some are funny, and some are just plain absurd. Take why pilots say "Roger" when they don’t mean "yes," or what "S.O.S." really stands for (spoiler: it doesn’t stand for anything). Let’s decode 10 of them.