We talked to the 49-year-old former heavyweight champ, acting as the captain (across from Quinton) for Triller's upcoming Triad Combat event on Nov. 27 ... and asked Briggs about coming face-to-face with his rival.

"We're gonna see each other, there's a press conference Wednesday, the weigh-ins Friday and the fights Saturday. I'm looking forward to it champ. When I look at him in his face and I tell him 'lets go champ', we're gonna see. I think personally he gonna defecate on himself. I think he gonna defecate, but he might not," Shannon says.

"If he don't defecate or urinate, he might be tougher than I thought."

🤢🤢🤢💩💩💩

Shannon and Rampage's beef ain't new ... the combat sports legends have been going back-and-forth on social media for months.

We also talked to Shannon about the concept -- fighting in a triangle -- an idea Briggs believes will lead to almost nonstop action.

"It's definitely gonna bring a lot of anxiety, pressure to someone who's never done it before. How do you train for something like that? You're used to training whether it's an Octagon or a ring, now you're fighting in a triangle."

Briggs continued ... "It's gonna be amazing. I'm looking forward to it. I think it's gonna lead to a lot more toe-to-toe slugging."

FYI, Matt Mitrione, Kubrat Pulev, Frank Mir and Mike Perry are among the fighters on the inaugural card.

For now, Briggs (2x heavyweight champion) and Jackson (former UFC light heavyweight and PRIDE middleweight champ) are just captains ... but if the 2 former champs scrapped, it'd be a hot ticket.