Rejoinders are quick responses to show that you are interested or paying attention.

(Oh) Really?
That's interesting.
Is that right?

 

Note how rejoinders are used in the following situations.

1. I just got a new job.
 Oh really? That's great!
2. I lost my wallet yesterday.
Oh really? That's too bad.
 

Rejoinders may also take the form of follow-up questions. Note how they are used in the following situations.

1. I just bought a new car.
 You did?
2. Johnny is in the hospital.
He is?
3. I'm going to Hawaii.
You are?