Cassie is recalling her first "freak-off" ... and she says drugs, alcohol and a bunch of baby oil were involved.

She said Diddy brought up voyeurism at some point in their first year together and she was 22 years old when she agreed to her first freak-off ... telling the jury she agreed because she wanted to make him happy.

Cassie says the freak-off happened at one of Diddy's homes in Los Angeles ... where a male escort was paid to dance and have sex with her.

She testified she took ecstasy and drank alcohol before the freak-off ... and said it was Diddy's idea to disguise themselves, so she wore a masquerade mask.

Last year's federal indictment against Diddy cites the "freak-off" parties ... calling them "elaborate and produced sex performances that Combs arranged, directed, masturbated during, and often electronically recorded."

Cassie says there were at least two sessions in the first freak-off ... and a session was over when the escort "finished."

She told the jury she felt dirty and confused, and knew that Diddy was happy with her. She also said she felt like she couldn't say no to the freak-off because she didn't want to make Diddy angry or upset after he shared this part of himself with her.

Cassie testified the freak-offs became more frequent ... happening weekly for years. She says her last freak-off was in 2017 or 2018 and she never slept during the freak-offs and would take ecstasy, Molly and cocaine.

She told the jury it was impossible to recall all of the freak-offs ... and she wanted them to stop because she felt humiliated, but she didn't have anyone to talk about it with.

Cassie testified she told Diddy she didn't want to participate in freak-offs ... gently broaching the subject with Diddy because she didn't want to anger him.

She says the freak-offs happened in Diddy's homes -- in Los Angeles, Miami, New York -- as well as in some of her homes, plus locations in Atlanta and Ibiza. She says there were freak-offs in hotels, too.

Cassie testified about the supplies needed for freak-offs ... Astroglide personal lubricant, condoms and Johnson's Baby Oil. She said Diddy told her she needed to use baby oil so she would be "glistening." Cassie testified there was once a kiddie pool filled with baby oil during a freak-off at a hotel and she got into the pool at Diddy's request.

She told the jury Diddy expected her to do freak-offs on her period ... even though she didn't want to.

Cassie also said she got urinated on during freak-offs, but she didn't want to be peed on and it was "disgusting" and "too much." She said she choked from having too much urine in her mouth and "no one could think I wanted it." She testified Diddy urinated on her -- and she didn't want anyone to urinate on her -- but it still happened "often enough."

She was asked point-blank why she didn't say no to being urinated on ... and she responded, "It was obvious I didn't want to be on the ground being urinated on by two men."

Cassie also testified they found escorts for freak-offs by searching Craigslist, at least initially.

For his part, Diddy's been staring at the jury during all of Cassie's testimony about urination ... and his kids and family look unfazed at the courthouse.

Cassie testified she needed drugs -- Special K, GHB, mushrooms, cocaine, ecstasy, Molly -- at every freak-off in order to disassociate and become emotionless to make it through. She told the jury Diddy took drugs at the freak-offs and sometimes so did the male escort.

She said she hated the freak-offs and the drugs made her not be present with the experience  ... and the ecstasy and Molly sometimes made her vomit, though she added that Diddy would tell her to continue with the freak-off anyway.

Cassie testified she did not want to continue having sex when she wanted to vomit, that GHB made her feel drunk and tipsy, that cocaine made her heart race and that mushrooms made the walls come alive.