Queen of the South (Reina del Sur) by Arturo Pérez-Reverte:

First of all, I should confess my laziness: I read the English translation
even though I can read Spanish. The translator chose to leave the profanity
in Spanish, so a side-effect of reading this book was that I managed to pick
up vernacular use of Spanish profanity. I think that's the best way to
teach foreign-language profanity: write an English text laced with
foreign-language profanity.

As for the book itself, meh. It covers the rise and fall of a female
druglord. In the author's attempt to portray the glamour and hedonism of the
drug world, he makes it look entirely unappealing and, well, squicky. I
didn't find myself caring about any of the characters, so I had no
motivation to read on, and working through the book was a chore. However,
reading this book has completely put me off the idea of indulging in illegal
drugs, because I don't want my money to support squicky people like I found
in this book.