(as) slick as a whistle smile
(adj) (Used to describe one's manner or movement) fast, skillful, or even and regular.
Wow! his head movement is as slick as a whistle! His opponent can't hit him.
She was as slick as a whistle when swinging herself over the gate.
(adv) In a fast, smooth, or skillful manner.
He negotiated as slick as a whistle and managed to reach a sweet deal.
Slick as a whistle, the driver avoided potholes, puddles, and pedestrians.
Very quickly
Very fast.
To help something run or work smoothly or successfully
Quickly and effortlessly
This simile was first recorded in 1830.