the term 'beef flaps' is used in a derrogatory fashion to describe the female genitalia, as they tend to, (especially when a female is aroused) resemble two peices of flappy beef, between the legs of the woman.

Slang. A term used for a rather large, flappy pair of labia majora which resemble a dangly cut of beef. (Think of two flapping sirloin steaks)

'Beef flaps' are usually dark red in colour, look slightly raw and bloddy and have a lot of veins and sinew running through them.