Daniel Cormier: The Insult Jon Jones Hates the Most Is ...

They've said some pretty nasty stuff to each other ... but Daniel Cormier says there's ONE insult that pisses Jon Jones off more than anything else.

DC was out in NYC promoting his big fight with JJ at UFC 200 in July -- when he told us he knows exactly how to get under Jon's skin ... and doesn't plan on stopping anytime soon.