Looking for a story ^^

I remember reading a story a looong time ago but I can't for the life of me remember the title. It's about a guy who either buys or finds a box of magic jewelry from some old scientist. He invites his friend and his friend's girlfriend over so they can test it on her. Anyway, the inflation happens when someone blows into this metal tube and inflates the person wearing one of the pieces of jewelry.

I think I got it from the overflowing bra, but I can't seem to find it anymore. I think I'm just not using the correct search parameters because none of the titles that show up from the search ring a bell. Any help is very much appreciated ^^