YOU SAID:
When your sister thinks you're stupid
INTO JAPANESE
あなたの妹があなたがばかだと思うとき
BACK INTO ENGLISH
When your sister thinks you are a fool
INTO JAPANESE
あなたの妹があなたがばかだと思うとき
BACK INTO ENGLISH
When your sister thinks you are a fool
That didn't even make that much sense in English.