Oh and I had this conversation recently. I'm pretty sure even some CW people would spot the trouble, though.
My friend: "And I'll have a diet soda."
Me: "Soda with breakfast? Wow, you really do love soda."
Friend: "Oh, well you know, it's diet, so it's healthy. All I ever drink is diet soda, I even use it to swallow my pills."
Me: "Wait, so you're saying that's literally all you drink? No water, even?"
Friend: "Nope! I haven't had any water in oh... hmm... probably two or three years now!"
She looked so proud of herself. I tried commenting that I bet at least some water might give her kidneys an easier life, but no luck there.