(from a low-intermediate level class)
Me: Belinda doesn't eat meat. What do we call someone who doesn't eat meat? Do you know the English name?
A student: Vegetarian?
Me: Excellent! Now—a harder question. In English, what do we call someone who doesn't eat meat, doesn't eat eggs, and doesn't drink milk?
Another student: Allergic.
I found this far too funny not to post.