Be all ears
Definition 1 of 1
Pro Tip 1/3Informal Use
Used in casual conversations among friends or family, not in formal situations. 
When you mentioned a surprise, I was all ears!
Pro Tip 2/3Positive Interest
Expresses a genuine and enthusiastic interest in what someone is about to say. 
You've started your own business? I'm all ears, tell me everything!
Pro Tip 3/3Exclusively Metaphorical
The phrase is never used literally; it's always figurative. 
He said he had a story to share, and suddenly the children were all ears.