How do you deal with a friend who flirts with your boyfriend?

There are these two girls that i know who are having trouble with the same girl because she keeps on flirting with their boyfriends. Flirting such as sitting on his knee, listening to the ipod together using the same head phone, hugging him from the back, being VERY touchy touchy. These 2 girls that i know are FURIOUS, but don't know what to say to this girl, because she's just the type of girl who just doesn't listen and doesn't care. I said to talk to her face to face but they don't know what to say. I rly need some good advice. Plz and Thank you!!!How do you deal with a friend who flirts with your boyfriend?
YOU NEED TO BE TALKING TO YOUR BOYFRIEND ANDS LET HIM KNOW WHATS GOING ON, LET HIM KNOW HOW YOU FEEL AND COMING FROM...THOSE GIRLS AINT GOT NONE TO DO WITH YOU BECAUSE YOUR BOYFRIEND IS THE ONLY PERSON THAT KNOWS WHATS GOING ON IN THE RELATIONSHIP....BUT IF THEM BITCHES CONTINUE TO GET ALL IN YO MAN FACE LET THEM BITCHES KNOW THAT IT AINT COOL TO BE TRYING TO TALK TO MY MANHow do you deal with a friend who flirts with your boyfriend?
They should talk to that girl. It's not about them being bossy girlfriends or anything but think of the image she creates for herself. That is if she doesn't want a bad rep on her head. Those girls should also have a nice lovingly talk with their boyfriends. I mean, I'm a dude and I would love that kind of attention from a chic. But if I am serious about a girl, some thing are just gonna have to be left behind and can't be allowed. What kind of Boyfriend would I be? What kind of trust does that inspire in my girl? Anyhoo, you guys are smart. Figure it out. It's either that or settle it the old fashion way: 3 'o clock this afternoon in the yard. Winner fights the inconsiderate boyfriends haha