YOU SAID:
I have to go pee really bad.
INTO JAPANESE
私は本当におしっこを行かなければならない。
BACK INTO ENGLISH
I have to go pee really.
INTO JAPANESE
私は本当におしっこする必要があります。
BACK INTO ENGLISH
I really need to pee.
INTO JAPANESE
私は本当におしっこする必要があります。
BACK INTO ENGLISH
I really need to pee.
That didn't even make that much sense in English.