A Phrase used when someone says something really odd, out of place, stupid, and/or perverted. Usually accompanied by throwing a flag or some other object (napkin, paper, shirt, etc...)
Group of friends, Ray Marcus and Pat chillin Ray: "Man, I finally got the pussy last night"
Pat: "That's wassup man"
Marcus: "I'm mad at you Ray, last night we were supposed to spend time together"
Ray & Pat "WHOA!!! FLAG ON THE PLAY!!!"