noun
foolish monkey
Refers to a monkey that acts foolishly or is considered foolish; may appear in folklore or as a metaphor for a silly person.
昔話にこけ猿が出てくる。
A foolish monkey appears in the old tale.
Compound of こけ (foolish) and 猿 (monkey). The exact origin is uncertain, but it likely arose as a descriptive term in folklore or everyday speech.