Naughty language. =(

I'm interested in hearing how you handle bad language in your class.  I teach PreK and still have one that obviously heard a BAD word... we're talking more than the "stupid" word... the F bomb with extra added on to it!!  My little one has said it quite a few times and just now saying it in my own classroom.  Said it while coloring with her classmates..not even in anger, but while playing.  This just makes me so sad.

One part of me says send to the principal right away (which is what the parents want) and another part of me says she learned it from someone.  She is seeking the attention she is receiving from this so if I choose to ignore it or make her punishment away from the other students (sitting away as we talk low and offer better choices of words) to minimize the attention.  Anything to make it not worth it to say it.

What is your best advice on this?  This is a 4-5 year old.