大おお口ぐちを叩たたく

expression, godan verb (-ku)

boast; brag; talk big

Idiomatic expression meaning to make exaggerated claims about oneself, often in a loud or arrogant manner. The literal image is 'striking a big mouth'.

• 彼かれはよく大おお口ぐちを叩たたくが、実じっ際さいには何なにもできない。

  He often talks big, but in reality he can't do anything.

• 大おお口ぐちを叩たたく前まえに、自じ分ぶんの実じつ力りょくを考かんがえたほうがいい。

  Before you boast, you should consider your own ability.