One of those sayings that never quite caught on, "I don't know him from Adam's off ox."
Do you remember the context and what famous president said it?
It was Bill Clinton replying to charges that he had received campaign contributions from a certain Chinese Busninessman. The amount was tiny compared to what we allow in campaigns now.
In olden times the "off ox" was the one farthest away from the man steering the plough. The ox team was staggered in such a way that one was closer to the plough operator.