I would be much more concerned about WHY she felt this way. Kids say all kinds of things. Obviously she can't blow them all up. However, she must have been really upset! If they focus on what she said and not on why she felt this way - then a really important event is being missed. I repeat, it doesn't matter where she picked up the language - she can always be taught more appropriate ways to express herself - its why she feels this way that needs to be dealt with first. Then once this has been dealt with you buy a book like "Words are not for Hurting" and teach her better ways to express herself. http://www.amazon.com/Words-Hurting-Ages-Best-Behavior/dp/1575421569/ref=sr_1_1?s=books&ie=UTF8&qid=1440993348&sr=1-1&keywords=words+are+not+for+hurting
Do you know what the scenario was where she threatened her classmates?
Was she being bullied and she said this in anger?