Synonym used when describing a loose girl's girly bits.
"Oi love, show us yer Fuckflap s."
"I was with this bird last tuesday. Met her in Club I, god almighty, she was wasted. Only like 15 and all. So anyway, yeah, she looked well easy. So I made my moves, and yeah yeah, eventually we got outside right. I ended up fucking her aganist the fire exit of the club. Bloody hell, I tell you, I ain't never seen fuck flaps like hers. Massive! "