Diddy had a one night stand with a street performer ... problem is, the guy says he was raped ... at least according to a new lawsuit.

The Bad Boy Records founder is being sued by a John Doe who claims Diddy orally raped him and sexually assaulted him anally after spiking his drink.

In the lawsuit, obtained by TMZ, the man claims he was singing and playing guitar on the street outside a popular Los Angeles nightclub in November 2022 when a man claiming to be a talent scout for Diddy invited him to a Diddy party.

The John Doe claims he was driven to a private home where Diddy invited him to sit down, have a drink and talk about his music aspirations. He says as the conversation progressed he complimented Diddy's necklace and Diddy asked if he wanted to see more of Diddy's jewelry collection.

The guy claims Diddy then took him to a private room, where John Doe suddenly felt drowsy, off-balance and slightly euphoric ... despite consuming only one drink.

He says the room had no jewelry and Diddy bluntly asked, "Have you ever sucked a d*** before?" He claims he told Diddy "no" and Diddy responded, "You should try it," while exposing his penis.

The guy claims Diddy forced him to perform oral sex, grabbing the guy's face and forcefully inserting his penis into his mouth. He says he became more incapacitated from the drugs Diddy gave him, and Diddy undressed him and assaulted him anally before leaving the room.

The next morning, the guy claims he woke up at the house to someone giving him an IV ... and he was driven back to the nightclub and dropped off ... never to hear from Diddy again.

He claims he's suffered pain, mental anguish, emotional torment, humiliation and shame as a result ... and he's going after Diddy for damages.

Tony Buzbee, the Texas attorney representing 120 alleged Diddy victims, filed the suit.