Flatty Mcgee Share definition Flag To be flat chested. A nickname often given to a girl with no boobs. Hey, look its Flatty Mcgee over there she's so flat. Flatty Mcgee by Gaby Malick November 11, 2010 0 0 Get merch Get the Flatty Mcgee mug. Buy Now — $32.95 See more merch