Script (guión): Idioms, ‘bat an eyelid’. If you don't bat an eyelid you don't show any reaction, emotion when shocked or surprised. My girlfriend was so scared of spiders that if she saw one in the house you would think that someone had been murdered, she would scream so loud. So I paid for her to be hypnotized so she would lose this fear. And now she doesn't even bat an eyelid if she sees a spider. I'm thinking of getting her, for Christmas, a pet tarantula.