O.J. Simpson hopped behind a mic and gave a rare interview this week ... but there's one topic he won't touch after nearly 3 decades -- who killed Nicole Brown and Ron Goldman.
The 75-year-old was a surprise guest on the Nelk Boys' "Full Send" podcast ... where he talked about his 9-year stint behind bars for armed robbery, his friendship with President Donald Trump, the Kardashians and a bunch of other subjects.
But, when the conversation turned to the 1994 slaying of his ex-wife and her friend, O.J.'s chatter came to a screeching halt.
"Right now, I'm not going to discuss any of that, all right?" O.J. said when asked whether he's pissed the "real" killer was never caught.
"I think that's a pretty obvious question. But, I'm not getting into that. I'm not going there."
O.J. was chill throughout the nearly 2-hour podcast -- laughing as he told stories -- but when the murders were brought up, his mood clearly changed.