YOU SAID:
i eat rocks for dinner
INTO JAPANESE
私は夕食に岩を食べる
BACK INTO ENGLISH
I eat rocks for dinner
INTO JAPANESE
私は夕食に岩を食べます
BACK INTO ENGLISH
I eat rocks for supper
INTO JAPANESE
私は夕食のために岩を食べます
BACK INTO ENGLISH
I eat rocks for supper
That didn't even make that much sense in English.