Why not add one board where you can use all your f-words, talk about sex and allll those other things that might be offensive to some people? With the warning to enter at your own risk?
Many forums of this size have one. You can simply refer people to that board if they act out of line, even move posts over there and keep the other boards 'clean' so you will.
It's a simple solution.
And about f-words etcetera, I'll just use Dutch cuss words instead, so only Dutch readers will understand. Who won't be offended by it because our culture's kind of different towards that

Feel free to use some as well:
- kut
- klote
- gotverdomme
- kutwijf
- lul
- schijt
...