YOU SAID:
Dude your sister is right. You are stupid
INTO JAPANESE
あなたのお姉さんは正しいですね。バカじゃないの
BACK INTO ENGLISH
Your sister is correct. you are stupid
INTO JAPANESE
あなたの妹は正しいです。バカじゃないの
BACK INTO ENGLISH
Your sister is correct. you are stupid
That didn't even make that much sense in English.