Wine teeth

I get the worst red wine teeth ever. Most people get a touch of wine teeth when they drink the red stuff, but mine are terrible! One glass of cabernet and my teeth are dark gray, plus I get this weird black lipliner effect to boot. What gives? Maybe I should just not drink red wine in public, ever, but I don't really care if I look like a gray-toothed weirdo, I'm just curious why it happens to me so much worse than everyone else. Or maybe I only think it's worse for me. No, I really do get it worse than everyone else, except for one of Eri's friends, who also gets the gray teeth, black lipliner combo.