[throwaway41968]

Lol idk what your experience is but mine is that verlan has basically permeated all casual conversations among everyone under 40. I guess you'd look a bit odd if you hung around the kind of people who take pride in not using any of that language but in practice virtually everyone uses verlan in one way or another.

Also, using slang isn't as frowned upon as it can be in America. Again, idk your experience but mine is that people swear left and right in casual conversation without anyone giving them a side glance. Of course in formal contexts such as addressing strangers in the street or greeting your baker you don't want ot, but the moment familiarity sets in you can be sure swearwords are going to pop all the time.