While Donald Trump Jr.[1] celebrated the new year at Mar-a-Lago surrounded by family and friends, his alleged former girlfriend Aubrey O’Day[2] was getting thrown out of the Hustler Club in Las Vegas.

O’Day had agreed to host a mock birthday party for Trump Jr., who turned 41 on New Year’s Eve, at Larry Flynt’s mammary mecca[3], but then balked at singing “Happy Birthday” when the cake was brought out.

“Her assistant said, ‘Get the cake out of here!’ and started pushing our bottle service girls, almost knocking one down,” the club’s Dave Bryant told me. “It was a nightmare.”

Bryant said his security team immediately escorted O’Day and her team to a waiting car.

O’Day wanted the event to be about herself, not Trump, Bryant said. “It’s like she was booked for a PETA event and arrived in a fur coat.”

Her reps did not reply to a request for comment.

Meanwhile, Trump Jr., in black tie as he addressed the hundreds of guests at Mar-a-Lago, joked about his family’s love of the limelight.

Flanked by brother Eric[4] and girlfriend Kimberly Guilfoyle[5], Trump said, “I remember when Eric and I were the youngest people in the room. Now we get to pass the torch.”

After introducing some of the next generation, Trump said, “One day, you guys will be doing this, and I will be in a wheelchair. You will push me off the stage to get the mike, because you can’t help yourselves — because you are Trump and you want the mike.”

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