flapping it

Flapping it is dialect originally from Manchester. It basically means being a chicken. It's usually used in arguments and fights.

during sexual intercourse, the sound two bodies make while knocking boots

A flap-flap is an alternate name for winged animals mostly pertaining to fowl and bats. Other mammals that have folds of skin that can act like wings such as sugar gliders and flying squirrels. Insects and other mammals that use their extra skin to maneuver can be their own genus of flap-flaps including stingrays, dragonflies, butterflies and honey bees with the exception of wasps who are just assholes.

shaking one's willy in an eccentric and exciting manner. often resulting in hilarious and wet consequences. can be used as a form of foreplay or to attract other people to engage in the mating process, much like a peacock displays her feathers to attract a mate. a male human will often display his willy in an appealing way to gain sexual prowess.

A person who chickened out and ran away from a challenge and / or a fight.

Labia majora and minora surrounding the exterior of the vagina.

a) Aerodynamic devices found at the trailing edges of aircraft wings, used to augment lift at a lower speed during takeoff and landing.
b) The meaty lips you love to nibble on when you go muff diving