YOU SAID:
you are a barbie girl
INTO JAPANESE
バービーの女の子をします。
BACK INTO ENGLISH
I will play a Barbie girl.
INTO JAPANESE
僕はメアリの遊びます。
BACK INTO ENGLISH
I will play Mary.
INTO JAPANESE
僕はメアリの遊びます。
BACK INTO ENGLISH
I will play Mary.
That didn't even make that much sense in English.