糞くその役やくにも立たたぬ

Meanings

completely worthless; utterly useless

derogatory

A strong, derogatory set phrase meaning something or someone is of absolutely no use. The literal image is 'not even useful as shit.' Used in informal, often angry or dismissive speech.

あんな奴やつは糞くその役やくにも立たたぬ。
That guy is completely worthless.
この説せつ明めい書しょ、糞くその役やくにも立たたぬな。
This manual is utterly useless.

Kanji

糞shit, feces, excrement
役duty, war, campaign
立stand up, rise, set up

Related words

役やくに立たたない
Neutral way to say 'useless.' 糞の役にも立たぬ is much stronger and vulgar.
無む駄だ
Means 'futile' or 'wasteful.' 糞の役にも立たぬ is more emotionally charged and directly insults the object's worth.

Written forms

糞くその役やくにも立たたぬ
Standard kanji-kana spelling for this fixed expression.
くその役やくにも立たたぬ
Kana spelling of the first part; sometimes used to soften the visual impact of the kanji 糞.
クソの役やくにも立たたぬ
Katakana spelling of the first part; adds emphasis or a rough, slangy feel.

Etymology

A fixed derogatory expression combining 糞 (くそ, 'shit') with the phrase 役に立たぬ ('not useful'). The literal meaning is 'not even useful as shit,' emphasizing total worthlessness.