YOU SAID:
Why would you ever say such thing, you idiot?
INTO JAPANESE
なんでそんなこと言うんだよ、バカ。
BACK INTO ENGLISH
Why are you saying that, you idiot?
INTO JAPANESE
なんでそんなこと言うの、バカ?
BACK INTO ENGLISH
Why are you saying that, you idiot?
That didn't even make that much sense in English.