Flapper Rapper Share definition Flag Someone who thinks they can rap but they can not. So they just flap their lips trying to rap about absolutely nothing. That guy can't rap, he's just flapping his lips & that's called a "flapper rapper". Flapper Rapper by 0808NAX February 27, 2018 0 0 Get merch Get the Flapper Rapper mug. Buy Now — $32.95 See more merch