Yeah, I feel your pain. Every Friday and Saturday night, I always have to turn up the music on my iPod. My twin sister and I are totally grossed out by it.
Just act natural. I mean, the best thing to do would probably tell them to be more quiet, but from personal experience, that's waaaay too awkward. If they want to talk to you about it, that's great (that is, if they know...).
But if you don't talk to them, just crank up the music, or go out with your boyfriend. Good luck...