A way for a military-American to tell a non-military American, "That's just war lingo, son." Bastardized by American gangster-wannabe youths who think they invented everything.
Vietnam Vet: We lit up those slants and toasted some marshmallows!
American Civilian: What did he say?
Other Vet: Oh, it's a Nam sayin'. He just said that we dropped some napalm on some Viet Cong guerillas and watched them die in the resulting fire.
American Civilian: HAHAHAHAHA!
"Know what I'm saying?"
"That n00b got pwned, nam sayin'?"