Is this in the slang lesson because it's a funny way of saying "shivering", or is it just a normal way of saying it?
what is the "vay" there for? it says it means "so," so I put "why are you shivering so much?" but it just says the answer is "why are you shivering?" So, why Vay?
Vậy can mean "like that", a particle attached onto the end of a sentence equivalent to thế. "Why are you shivering like that?" Also acts to turn the sentence or phrase into a question.