Diddy Rejected Plea Deal, Lawyers Call Him A 'Swinger' Not A Criminal

Diddy rejected a plea deal federal prosecutors offered him ... and, his lawyers have shown their hand as to the main crux of their defense -- claiming he's simply a swinger, not a criminal.

The rap mogul was in a Manhattan courthouse Friday morning for a hearing that touched on a series of topics ... during which Rolling Stone reports his prosecutors revealed they did offer Diddy a deal -- and, he flat out turned it down.

No further details of the deal have been made public ... but, it's long been believed Diddy was offered one -- and, now we know those rumors are true.

Diddy's team also argued he may have lived a swinger lifestyle ... but, he's never done anything inappropriate or criminal -- with the head of his legal team, with Marc Agnifilo adding being a swinger is so common the mogul probably didn't think twice about it.

Prosecutors argued that they didn't want the defense to use other examples of other prominent people hiring prostitutes ... and Agnifilo assured the court he wouldn't -- though he did say he was entitled to establish that some alleged behavior was "part of the lifestyle."

Among the other things discussed during the hearing ... prosecutors claim Diddy may have made one of the alleged victims get a medical procedure -- which they say is related to the sex trafficking charges he's facing.

The judge is also allowing prosecutors to show the video of Diddy beating up Cassie ... and prosecutors say the person who filmed the surveillance video on an iPhone 6 will testify.

Cassie is scheduled to testify against Diddy, along with three other alleged victims who are all supposed to remain anonymous during the trial.

Diddy has pled not guilty to all five charges he's facing -- two counts of sex trafficking, two counts of transportation to engage in prostitution, and one count of racketeering.