noun
monkey show
Literal meaning: a performance featuring trained monkeys. This sense is the basis for the idiomatic use.
昔、猿芝居は縁日で人気があった。
In the old days, monkey shows were popular at festivals.
noun
bad acting; overacting; unconvincing performance;
Idiomatic use: describes poor, exaggerated, or transparent acting, or any clumsy attempt at deception. Often used critically.
彼の演技はまるで猿芝居だ。
His acting is just like a monkey show—terrible and overdone.
そんな猿芝居にだまされるわけがない。
There's no way I'd be fooled by such clumsy subterfuge.