Over Yom Tov while at someones house, and waiting for kiddush to be said, our host took out a silver kiddush cup. My mom, trying to make conversation said "We don't use a silver kiddush cup at our house because we don't like the taste of the wine after metal, so we use glass"
One of the kids was like "well yea, it ends up with a metalic taste."
But her father said "Yes, thats true, wine tasters use only glass cups, but for shabbos, you're supposed to use silver."
Maybe there's a halacha I'm aware of, but I doubt it. I highly doubt one has to use silver on shabbos. Infact, if one had to use silver on shabbos, then I'd be very concerned for the members of my shul, and many other shuls, when there's a kiddush. Because not only do they not use silver, but they use disposables plastic cups, which are as far from silver as I can imagine. And this isn't just a few "modern" people in my shul, the lack of usage of a silver kiddush cup is something I've seen in many shul's.
I was so fed up already, with all the crap I heard over Yom Tov (rice checking, anti-South Park- will blog about later), that I didn't bother answering him, and believe me, with my big mouth I wouldn't have been nice with my answer either.
I hate when a chumra or minhag is given halachic status when it clearly isn't one. There is nothing more frustrating in the entire world.