Surgeon general warning: if you get easily offended please skip this post. Move along.
I guess it is true that one of the first things people want to learn when starting a new language is the profanity… which in my case caused a couple of hilarious situations, as I came to Finland being able to utter only "kiitos" (thanks) and "perkele" (a general swearword of very strong intensity).
One of my first encounters with other vocabulary was in the public transport. I used to live in a rather bad area (for the standards here) of east Helsinki and for a long time I would hear teenagers finishing their sentences with something that sounded like "tu". Something like "Yadda yadda yadda tu, yadda tu. Tu, tu, tu". Further down the line I understood that they meant "vittu" (cunt, but used as the local alternative to fuck).