Judge Threatens to Remove Diddy From Courtroom for Looking at Jurors

Sean "Diddy" Combs' better quit making faces at jurors in his federal trial, or he'll be booted from the courtroom ... that's the stern warning the judge hit him with Thursday morning.

The 17th day of the trial began with Diddy's defense team peppering Bryana Bongolan on cross-examination -- questioning her about the alleged incident where she says Diddy held her over the edge of a balcony 17 stories above the ground.

After her testimony, once jurors left for a break, Judge Arun Subramanian admonished Diddy defense lawyer Marc Agnifilo for his client's courtroom behavior ... pointing out Diddy was "nodding vigorously" while staring down jurors.

The judge threatened sanctions, including possibly barring Diddy from the courtroom.

While he stopped short of saying it, the judge's concern seems to be Diddy's behavior could sway jurors -- conveying to them he agrees with questions from his attorneys or the answers Bryana was giving at the time.

During the cross-examination, the defense dug into the date Bongolan provided to the court -- September 26, 2016 -- for when Diddy allegedly held her off the balcony. The defense argued Diddy couldn't have been in L.A. that day because he was traveling on the East Coast on the "Bad Boy Family Reunion Tour."

The defense also pointed out Cassie and Diddy attended an event in New York City on September 26 ... and a hotel room at the Trump International in Manhattan was booked under his alias, "Frank Black," from September 24 to September 29, too.

The defense didn't let up, demanding Bryana explain how a person could be in two places at once. Bongolan did not have an answer for the question.

On redirect, the prosecution asked why Bryana didn't know the exact date of the incident -- and, she replied it was simply a long time ago. The prosecution later clarified -- using a text Cassie sent to Kristina Khorram's phone -- that the incident may have occurred on September 30, not September 26 as Bryanna said.

Remember, Bongolan says she was either smoking or about to smoke a blunt with Diddy out on a balcony when she says he grabbed her and held her over the edge ... approximately 17 stories in the air.

She says he yelled at her, "You know what the f*** you did," Bongolan testified ... before she says he pulled her back onto the balcony and slammed her into the furniture.