While shooting the 13th season of The Apprentice, Donald Trump repeatedly used a racial slur to refer to rapper and contestant Lil Jon—even after several producers urged him to stop, three staffers on the show told The Daily Beast.

During an episode of a season that first aired in 2013 (dubbed All-Star Celebrity Apprentice), the “Turn Down for What” singer was tasked, along with the other celebrity contenders, with mounting competing displays around and inside glass trucks in order to promote hair-care products. In the heat of competition, Lil Jon bought and donned an Uncle Sam costume to help advertise the “beautiful” hair product.

During the day’s shoot, Trump himself caught wind of this gimmick and began referring to Lil Jon around Apprentice staff as “Uncle Tom” instead of Uncle Sam.

“Look, he’s Uncle Tom!” one longtime Apprentice staffer recalled Trump blurting out at least twice. The staffer said Trump was utterly tone-deaf to the racially charged history of the term, which is used to deride a black man deemed to be subservient to white people.

It didn’t take long for multiple producers on the show to begin frantically attempting—in vain—to get the former real-estate mogul to stop calling Lil Jon an “Uncle Tom.” According to two sources from different departments on the production (speaking on the condition of anonymity due to strict non-disclosure agreements), one reason producers were freaked out was that comedian and talk-show host Arsenio Hall (who is also black) was a guest star on that episode, and had heard Trump refer to Lil Jon in the derogatory way.

Hall made his displeasure with the use of the term clear, and staff sprang into damage control.

“We kept trying to explain to [Trump] that that’s not a word you can use, that it’s offensive,” another Apprentice employee told The Daily Beast. “One of the executive producers had to call him up directly to [plead with] him not to say it, and Trump was like, ‘No, that’s a saying, it’s Uncle Tom.’ There are several takes in the footage of the dailies that has him trying to figure out the difference between ‘Uncle Tom’ and Uncle Sam. He just couldn’t grasp that it was offensive… When [Trump] decides he wants to do something, that’s his way.”

Another Apprentice staffer of several years who helped intervene in the “Uncle Tom mini-crisis,” as the source dubbed it, confirmed that “multiple producers had to try to instruct him” but that “somehow none of it stuck.”

“It was not like he was saying the n-word, or anything,” the staffer continued. “But I couldn’t understand why he wouldn’t just realize he was being offensive with that particular term!”

According to these staffers, the producers’ “Uncle Tom” advice was brushed off by a decidedly politically incorrect Trump for the rest of the shoot. This was, by the way, the same season of Celebrity Apprentice during which Trump told female contestant Brande Roderick that it “must be a pretty picture, you dropping to your knees.”

Hall's publicist did not respond to a request for comment on this story. The Daily Beast reached out to the Trump campaign for comment and within 12 minutes of receiving our inquiry, campaign spokeswoman Hope Hicks emailed back, “This is simply untrue.”

However, on Friday evening following the publication of this Daily Beast article, Lil Jon tweeted a statement confirming our report, and adding a detail from the Apprentice boardroom.

"When this 'Uncle Tom' incident happened on Celebrity Apprentice in the boardroom several of my castmates and I addressed Mr. Trump immediately when we heard the comment," the rapper wrote on Twitter. "I can't say if he knew what he was actually saying or not, but he did stop using that term once we explained [its] offensiveness. I also want to be clear that I don't agree with many of the statements Mr. Trump has said during his current run for President."

(In late 2012, an anonymous staffer shared a brief version of this story on the controversial gossip blog The Dirty but it was never corroborated until now.)

There are myriad accounts of Trump acting inappropriately, perhaps even criminally, during shoots of his NBC series, sometimes toward his celebrity contestants and friends. On Thursday, for instance, The Daily Beast reported that Trump had repeatedly demeaned Marlee Matlin, an Oscar-winning actress who competed on the show’s 11th season, as being mentally “retarded”—all because the actress was deaf. Summer Zervos, a former contestant on Season 5 of The Apprentice, came forward on Friday with new accusations of sexual assault by Trump, claiming that he “thrusted” his “genitals” on her.

And the “Uncle Tom” Lil Jon incident was hardly Trump’s only racially insensitive move on The Apprentice. There was a time when Trump once wanted to create a black-versus-white season of the series.

It’s not much of a surprise that Trump, the reality-TV star, handled race issues so poorly. As the Republican presidential nominee this year, Trump has overseen a campaign black-outreach effort that has been nothing short of a train wreck. And the director of his campaign’s African-American outreach team? It’s none other than Omarosa, Trump’s go-to, wacky reality-TV villain from The Apprentice.

“What do you have to lose?” Trump asked black voters in August, imploring them to vote Republican this presidential election. “You’re living in poverty. Your schools are no good. You have no jobs. Fifty-eight percent of your youth is unemployed. What the hell do you have to lose?”

In terms of polling among black voters, including in crucial swing states, Donald J. Trump is currently rapidly approaching a whopping zero percent.

Editor’s note: This story was updated with Lil Jon's statement on Saturday, Oct. 15 at 9:07 a.m. ET.