prick up its ears
prick up (one's) ears
1. Literally, of an animal, to raise its ears, as upon hearing a sudden noise. The dogs pricked up their ears and started staring outside. I wonder what they heard.
2. To pay sudden close attention to something one overhears. Be sure to prick up your ears if anything about the case is mentioned. I can't help but prick up my ears if I hear someone say my name—even if they aren't talking about me.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
prick up its earsand prick up one's ears
Fig. [for an animal or a person] to become attentive. (The animal will adjust its ears toward the sound.) The sound made the dog prick its ears up. When Fred heard his name, he pricked up his ears. She pricked her ears up when she heard her name.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.