YOU SAID:
It's my birthday today and my partie tomorrow!!
INTO JAPANESE
今日は私の誕生日と私の側を明日だ!
BACK INTO ENGLISH
Today is my birthday and my side tomorrow!
INTO JAPANESE
今日は私の誕生日と私の側を明日です!
BACK INTO ENGLISH
Today is my birthday and my side tomorrow!
That didn't even make that much sense in English.