Adjective
quick on the draw (comparative quicker on the draw, superlative quickest on the draw)
(idiomatic) Characterized by rapid response, as to a verbal remark or to a new situation; quick to act.
It's easy to be quick on the draw when no one has got real bullets. Timothy Olyphant
The people I grew up around who I really liked were quick on the draw. It always just wowed me. And my mum would make weird funny comments. I can see in myself her self-deprecating, hippie humour. I can't take myself too seriously. Drew Barrymore