Searching for a story

I can't for the life of me remember the title, or whether I got it here or at the Overflowing Bra. Anyway, the story is about a guy who finds a box of jewelry at a rummage/estate sale. The jewelry has some sort of magic affixed to it and they experiment on his friend's girlfriend. The magic works by making the girl wear a piece of the jewelry and her partner blows into a tube/whistle like thing.

I hope I was detailed enough ^^