ケツが青あおい

expression, i-adjective

wet behind the ears; inexperienced; immature

Idiomatic expression literally meaning 'butt is blue', from the bluish tinge of children's buttocks. Used to describe someone who is inexperienced, immature, or still a novice.

• まだケツが青あおい新しん人じんに、そんな大だい事じな仕し事ごとは任まかせられない。

  We can't entrust such an important job to a newbie who's still wet behind the ears.

• 彼かれはケツが青あおいけど、やる気きはある。

  He's still green, but he's motivated.