YOU SAID:
I made him an offer he couldn't refuse.
INTO JAPANESE
私は彼に拒絶できない申し出をした。
BACK INTO ENGLISH
I made an offer that he could not refuse.
INTO JAPANESE
私は彼が拒むことができないという申し出をした。
BACK INTO ENGLISH
I made an offer that he could not refuse.
That didn't even make that much sense in English.