When learning another language, don’t try swearing to sound cool

Beyond the usual reason that in highly respectful societies will come off as extremely rude, it's because it will sound dissonant and discordant, and for some reason make the native speakers around you feel worried.

You don't want to pick up slang and swear is because the cool usage is likely super subtle in a way you will not understand. Really great perspective I got was being on the receiving instead of giving side of this. In Asia I remember meeting someone who learned English as a secondary language and was swearing in English in a playful way to be more colloquial with me, but I found it less endearing than I imagined and more worrisome. As in worrisome on the other person's behalf. I don't know why I felt that, but it's due to something along these lines.