That was a topic on an NFL players edition of "Family Feud" Thursday night ... and Marcus Peters' answer was so bad -- the Baltimore Ravens star was clowned like hell over it!!!

Here's how it went down ... Peters was facing off with Adrian Peterson when Steve Harvey asked the two, "What's the first thing a stripper takes off?"

Peters -- confident as hell -- buzzed in and blurted out, "Panties!"

PANTIES?!

The answer was immediately hit with a red X ... and when Harvey got over to Peterson's NFL legends team -- they laughed their asses off over it!!

"See, that's the difference between old school and new school," Harvey said. "Panties, right now!"

To his credit, Peters laughed it all off with the rest of the guys ... and, hey, watch the clip -- it wasn't like anyone else's answers were much better!