shoot from the hip

verb2

1. •
   To discharge a firearm while it is held near the hip, without taking time to aim via the gunsights.

   • “As to their rifle fire, it was useless.” “They shoot from the hip, and don’t seem to aim at anything in particular.” — 1914
2. •
   (figurative) To speak or act quickly based on first impressions, without carefully studying the background information, wider context, etc.

   • Trump is shooting from the hip, spraying insults 360 degrees, telling lies, stoking fears and making threats that many in our military and the F.B.I. would refuse to implement. — 2016