expression
futile effort; like pushing against a curtain
Idiomatic expression meaning that an action is pointless or has no effect, like pushing your arm against a shop curtain (暖簾) which just gives way. Often used when arguing or competing with someone who doesn't respond.
彼にいくら文句を言っても暖簾に腕押しだ。
No matter how much you complain to him, it's like pushing against a curtain.
あの上司と議論しても暖簾に腕押しで、何も変わらない。
Arguing with that boss is futile; nothing changes.
Also means a futile effort, but specifically like driving a nail into rice bran—no resistance and no effect. 暖簾に腕押し emphasizes the lack of response from a person or situation.
Literally 'a clamp on tofu', meaning an action that is completely ineffective. Similar in meaning but uses a different metaphor.
From the image of pushing one's arm against a shop's entrance curtain (暖簾), which offers no resistance. The exact origin is uncertain, but it is a well-known Japanese idiom.