Smundies Share definition Flag Noun. Articles of underwear, usually smouldering or recently burnt. Abbreviation of "smouldering undies" Shit man! Your undies; they're on fire! - Damn, I guess they're smundies now. Smundies by The Smunder April 24, 2011 0 0 Get merch Get the Smundies mug. Buy Now — $32.95 See more merch