A disorder which causes a female to have two genitillas. Rarely, both anuls function.

Whereas a normal woman's vagina can only take so much punishment before becoming sore, a woman with a "double-jointed" vagina can have sex with multiple partners (4+) throughout the day with no ill effects.

When a vagina has two canals. (holes)

When a girl has larger thighs and it looks like she has a second libia - or a second vagina. So the slang phrase "double vagina" or "double vag" is a another way of calling a girl fat. Often used by assholes who want to shame you.