expression, i-adjective
insane; crazy; nuts; out of one's mind
Colloquial expression meaning someone is mentally unstable or acting irrationally. Often used in casual speech.
See also: 頭のおかしい
あんなことを言うなんて、彼は頭がおかしいんじゃないか。
Saying something like that, he must be out of his mind.
こんな時
I think the neighbor is crazy, vacuuming at this hour.