Naitch and the UFC star had an "altercation" at a bar recently ... and the footage of their wild trash-talkin' session that turned violent quickly spread on social media.

Of course, many rightfully suspected there wasn't any real bad blood between the two -- after all, they've starred in commercials for Car Shield in the past ... and actually have another spot dropping next week.

But we reached out to Chandler about the whole thing ... and he explained what exactly went down.

"It was a work," the lightweight contender told TMZ Sports. "Ric was teaching me the art."

Regardless, it's still just as funny to see the two get in full character for the clip ... with 74-year-old Flair showing he's still just as good with his lip service, and 37-year-old Chandler slapping him and doing a double leg takedown.