How to stop a friend from too much ?

I'm a junior at UW-Madison and it's a pretty big party school. There are always tons of frat parties down Langdon street and my best friend dishes out to me all her dirty stories and I'm a little worried about her. Sometimes she has with up to 4 different people on nights she goes out. This isn't what concerns me though, because we're in college and like to have fun and whatnot, but she tells the guys she gets intimate with that they can in her without a condom and no protection. How can I get her to use protection before something bad happens?