In Britain, used to refer to the labia majora of the female vagina. Otherwise known as the vaginal "lips".

Can be used as a derogatory term, in the same way that cunt, dick, asshole would be used.
That chick has huge fanny flaps.

I'd like to wrap my fanny flaps around that guy's cock.

Shutup fanny flaps.
by Dave March 5, 2003
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A competition to see who can flap out the grossest fanny smell
She's the regional champion at smelly fanny flapping, what a whiff worth a sniff
by mitch00uk March 21, 2015
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When vagina flaps are disportportionally large in comparison with other body parts. Flaps are slighyly loose and flappy, and may clap or flap during a fanny fart.
"Warren, was that a machine gun?" "No sally that was just Jenny's floppy fanny flaps".
by haynah September 17, 2005
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when a thong is so tight it looks like there is 4 flaps- fanny 4 flaps
she was dam good looking but she had a fanny 4 flaps
by Iva humpalot and aloto vagina December 7, 2005
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