ばかたれ

noun

blithering idiot; bloody fool; total moron; dimwit

Strongly derogatory term for a person considered extremely foolish or incompetent. Often used in anger or as an insult.

• このばかたれ！何なにをやっているんだ！

  You blithering idiot! What are you doing?!

• あんなばかたれに任まかせたら、仕し事ごとがめちゃくちゃになる。

  If you leave it to a total moron like that, the work will be a mess.