prick up its ears
prick up (one's) ears
To suddenly pay close attention to something. 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.
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.