YOU SAID:
Why in the world should I do it
INTO JAPANESE
なぜ私はそれをしなければならないのか
BACK INTO ENGLISH
why should i do that
INTO JAPANESE
なぜそれをすべきなのか
BACK INTO ENGLISH
why you should do it
INTO JAPANESE
なぜあなたはそれをしなければならないのですか
BACK INTO ENGLISH
why should you do that
INTO JAPANESE
なぜあなたはそれをしなければならないのですか
BACK INTO ENGLISH
why should you do that
That didn't even make that much sense in English.