IDIOMS

bat an eyelid

(idiomatic) To react in any slight way; to respond.

Example:   When laptop computers first came out they were something of a novelty. These days, nobody bats an eyelid.
1914, Edgar Beecher Bronson, The Vanguard‎, page 155:
  […] he got the drop on Cox, the only time I had seen or heard of its being done — had his pistol out and stuck in Cox's face before Cox could bat an eyelid.
2006, Pete Takeda, An Eye at the Top of the World, page 116:
  If you were to walk into a salon in America after a few 10–12 hour days of sweaty, dusty travel with no shower, you'd probably be politely asked to leave and not return until you've cleaned up. But here in a land whose resources and infrastructure cannot sustain such frivolity, the barber doesn't even bat an eyelid.
2007, Fionn Davenport, Dublin Encounter‎, page 153:
  Dublin's not a bad place to be gay. Most people wouldn't bat an eyelid at public displays of affection between same-sex couples […]