Emphatic questions

 Adding a wh-word at the end of a statement to make a question

Spoken English:

In speaking, we can sometimes turn wh-questions into statement questions:

What’s today’s date? or Today’s date is what?

1-  Declarative 

We do this especially when we are checking information that we have already been given or when we want to quickly check a particular detail. These are less formal than full wh-questions:

You have a dog  -   You have a what?

Your dog is in the yard -  Your dog is where?

2-  Surprise.

  "Hi mom. I thought I'd give you a call to tell you I love you."

"Oh that's so sweet darling!"

"And to let you know I cut off all my hair."

"You did WHAT!?"

3- To clarify meaning

Wife: "Darling, where did you put the mrphmnm?"

Husband: "Where did I put the what?"

"I took your mrphmm."

"You took my what?"