Shoot from the hip
Definition 1 of 2
Pro Tip 1/3Quick Decisions
The phrase is often used to describe someone who makes decisions or reacts spontaneously. 
During the meeting, she had to shoot from the hip to solve the unexpected issue.
Pro Tip 2/3Impulsiveness Caution
Be aware that 'shoot from the hip' might suggest a person's actions or decisions could be reckless. 
I admire his energy, but his tendency to shoot from the hip gets him into trouble.
Pro Tip 3/3Informal Setting
Used in casual conversation, could be inappropriate in formal contexts like business discussions. 
You're in a boardroom, not a chat room; don't shoot from the hip here.