三下兩下

quickly and effortlessly (idiom)

three / 3

down / downwards / below / lower / later / next (week etc) / second (of two parts) / to decline / to go down / to arrive at (a decision, conclusion etc) / measure word to show the frequency of an action

two / both / some / a few / tael, unit of weight equal to 50 grams (modern) or 1⁄16 of a catty 斤[jin1] (old)

twice / for a little while