Donald Trump Jr. was dubbed "Diaper Don" for drunken habits while at the University of Pennsylvania, according to a new book
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Donald Trump Jr. has been known by more than a few titles over the years: executive vice president of development for The Trump Organization, father, boardroom advisor on The Apprentice and, now, First Son. But according to Vanity Fair senior reporter Emily Jane Fox’s new book, Born Trump, the president’s eldest son was once known by a lesser-known moniker, bestowed on him during his college years: “Diaper Don.”

While an undergraduate at the University of Pennsylvania, Trump Jr. reportedly earned a reputation around campus for his rowdy, inebriated habits — notably, passing out in his classmates’ rooms, and wetting their beds.

“Diaper Don would wake up in some stranger’s dorm room or off-campus apartment or bedroom in his frat house, covered in piss, walk back to his own room, and get blitzed that evening or the next anew,” Fox writes.

The young Trump’s rambunctious reputation only intensified on a spring break trip to Jamaica amid March Madness frenzy, Fox writes. Drunk and bitter over a basketball loss to Florida State, Trump Jr. stood up on a table and chanted to Florida students, “That’s all right! That’s okay! You’re gonna work for us someday.”

“These were kids from state school,” one Penn student at the bar that day recalled to Fox. “The subtext wasn’t hard for anyone to figure out.”

Meanwhile, a spokesperson for Donald Trump Jr. refutes these details from the book, telling PEOPLE: “Both of these ‘claims’ are simply false. Don, who is now 40 years old, would be the first to admit that he enjoyed college, that said, both of these stories just aren’t true.”

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The book, which explores the upbringing of President Trump‘s five children with three wives, also describes Trump Jr., 40, as being later known as a cheapskate. When his eldest child Kai’s all-girl Manhattan private school, Spence, was planning a parent fundraiser to build a gymnasium, Trump Jr. balked, the book describes:

” ‘I think this sounds great,’ he said loudly enough for the other parents to distinctly remember it years later. Kai loved sports, he told the group, and so he could see her benefitting from the addition. … ‘I mean, we’re not going to give money,’ he said in front of the group. ‘But I am more than happy to lend my expertise to the building process.’ The rest of the parents turned beet red.”

Trump Jr. does not deny his history of drinking in college and for some years after graduation. “To be fairly candid, I used to drink a lot and party pretty hard,” he admitted in a 2004 interview with New York magazine. “And it wasn’t something that I was particularly good at. I mean, I was good at it, but I couldn’t do it in moderation.”

A friend who went to frat parties with Trump Jr. also told PEOPLE last year that, in college: “Everyone was warned to stay away from Donnie Trump.”

Trump Jr. has said he’s been sober since 2002. And this past weekend the father of five spent the holiday weekend playing golf with his children.

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It was his first Father’s Day as a single dad, since estranged wife Vanessa filed for divorce in March. But the pair have remained friendly, and Vanessa wished him well on Sunday.

Happy Father’s Day times 5 @DonaldJTrumpJR,” she wrote on Twitter, alongside a photograph of the 40-year-old smiling with their five children together: Kai Madison, 11, Donald III, 9, Tristan, 6, Spencer, 5, and Chloe, 4.

Born Trump is on sale Tuesday.