atama no neji ga hazurete iru lit. ‘the screw in your head has come off’
Japanese idiom, casual. Someone is a bit crazy, or is acting as if they’ve lost their mind.
Draft Not yet checked by a native Japanese speaker.
How do people use 頭のネジが外れている
?
Casual and a bit rude, said among friends about someone whose ideas or behaviour seem unhinged: “あいつ、頭のネジが外れてるよ”. In speech the い of いる usually drops (外れてる). People also say the screw has “flown off” (飛んでいる), which is the form Tatoeba has.
Also said 頭のネジが飛んでいる
頭のネジが外れている
in real sentences
-
トムは頭のネジが飛んでいる。
Tomu wa atama no neji ga tonde iru.
Tom is crazy.
Tatoeba, sentence by OrangeTart, translation by CK, CC BY 2.0 FR
Where does 頭のネジが外れている
come from?
I found no source that traces it. ネジ in the sense of a screw is recorded in Hepburn’s Japanese-English dictionary of 1867 (Nihon Kokugo Daijiten via Kotobank), so the idiom can’t be older than that. English has the same picture (Wiktionary quotes “have a screw loose” from Trollope in the 1870s) and so does German, which makes a borrowing possible, but that’s a guess.
Mistakes learners make with 頭のネジが外れている
Using it as a neutral description of someone with a mental illness. It’s a joking insult for wild or reckless behaviour, and aimed at a real condition it sounds cruel.
Other Japanese idioms like 頭のネジが外れている
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?
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