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Daniel Cormier is finally revealing what he meant when he accused Jon Jones of "sandblasting prostitutes" ... and shocker, it involves a whole lotta cocaine!

Remember, DC fired the insult at Jones during their nasty exchange at the UFC media event in Dallas last week ... though everyone, including Jones, seemed baffled by what he meant.

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So, we went right to the champ to get an explanation and he spilled the beans ... even telling us which UFC superstar first introduced him to the term.

We also asked Cormier if he thinks Jones will stay clean long enough to make it to their showdown at UFC 214 on July 29th.