YOU SAID:

He's doing a really big sad.

INTO JAPANESE

彼は本当に大きなって悲しい。

BACK INTO ENGLISH

He is really big so sad.

INTO JAPANESE

彼は本当に大きいので悲しい。

BACK INTO ENGLISH

Sad because he is really big.

INTO JAPANESE

彼は本当に大きいので悲しい。

BACK INTO ENGLISH

Sad because he is really big.