聞き捨てならない
also: ききすてならない
Meanings
1
inexcusable; unpardonable; can't be ignored
Used when something said is so offensive or unacceptable that one cannot let it pass without comment. Often follows a statement that the speaker finds outrageous.
His rude remark is inexcusable; I can't let it pass.
That joke is unpardonable; I can't just ignore it.