expression
burying one's head in the sand; hiding the head but not the bottom
Proverb meaning that someone tries to hide a fault or weakness but leaves another part exposed, making the attempt futile. Often used to criticize half-hearted concealment.
彼は自分のミスを隠そうとしたが、頭隠して尻隠さずで、すぐにばれてしまった。
He tried to hide his mistake, but it was like hiding his head and leaving his bottom exposed—he was found out right away.
その言い訳は頭隠して尻隠さずだ。
That excuse is a case of hiding your head but not your bottom.
A traditional Japanese proverb. The exact origin is uncertain, but it is thought to derive from the image of a pheasant or other bird that hides its head in the grass, believing itself concealed while its body remains visible.