YOU SAID:
My sister is the stupidest
INTO JAPANESE
私の妹はバカです
BACK INTO ENGLISH
My sister is stupid
INTO JAPANESE
私の妹はばかです
BACK INTO ENGLISH
My sister is an idiot
INTO JAPANESE
私の妹はばかです
BACK INTO ENGLISH
My sister is an idiot
Come on, you can do better than that.