A Swearing Character

I tend to avoid (or often, have no need for) foul language in my writing.  With a few judiciously chosen exceptions, I do not have characters curse.  This is usually not hard to do.  My characters often have conversations in my head without my active prodding, so I simply write down what works.  My characters usually have no need for swearing.

That is, until one of my new characters started talking.

She doesn’t have a name yet, and I barely have any story for her.  So far, all that I have is a conversation between two characters and a lead-in to that conversation.  With only that, I already know that the female character has a foul mouth.

I have a few choices here.  This character is for my NaNo novel, so there’s some time to contemplate.  (Because of the NaNo rules, I can’t even start writing anything for the story other than outlines and character development.)  One choice is to just let her be herself and write a story that’s (likely) full of words my mom wouldn’t approve.  Another is to let her swear but using creative, made up “swear words” instead; since she’s of a fantasy race, this might work.  The third possibility is to find a way to get across this interesting and valid character trait without the actual use of language.  No matter what I choose, she’s going to be a crazy character to write.

Anybody else have to deal with a foul-mouthed character?  How did you handle it?