Never. You just need to learn the social weight of the words you use in the context your in. I’ve heard 10 year olds shouting the F word in class and their teacher never batted an eye because they didn’t speak English there. Caught me off guard, but nobody “gets” that it’s bad. It’s just a funny sound people say a lot in foreign films to them. Someday they’ll embarrass themselves in an English speaking country and figure it out.