not on

Australia Britain informal

(informal, Britain, Australia) Unacceptable or impossible.

Japanese Meaning

受け入れがたい / ありえない / 絶対に不可能

Asking me to cover your parking fine when you were clearly at fault is not on.

あなたが明らかに悪いのに、私に駐車違反の罰金を払わせるなんて許されないよ。

Sense（1）

(informal, Britain, Australia) Unacceptable or impossible.