It wasn't a memorable post-Republican debate experience for Herman Cain on MSNBC Wednesday evening.

Interviewed by the cable network's panel, Cain was challenged by Washington Post columnist Eugene Robinson about his plan of Social Security going the route of Chile's model.

"I covered South America, I covered Chile," Robinson said. "The Chilean model is privatization of the pension system, so, what's the difference between privatization and privatization?"

"Sir, with all due respect, it is not, it is personalization," Cain said.

"Workers in Chile, they have an account that they retire with their name on it," he added. "That's not privatization. The word 'privatization' is used to try and kill off the idea without even trying. With all due respect sir, it is personal retirement accounts, and that is what I'm proposing."

That was only the beginning of Cain's rocky appearance, which also saw his "9-9-9" plan come under heavy scrutiny and laughter from MSNBC's crew.

WATCH: Video from MSNBC, which aired on September 7, 2011.