Chances are relatively high that you have, or have had, a penis or a vagina.
And I hope you still have at least one of them.
However, I know lots of people who own cars that have no idea how to change their oil.
I feel like I’m mixing metaphor with innuendo, now…
Point is, I bet there’s still a good deal that you don’t know about those naughty (or nice) bits:
From the Online Etymology Dictionary:
…1680s, medical Latin, from specialized use of Latin vagina “sheath, scabbard, covering; sheath of an ear of grain, hull, husk” (plural vaginae), from PIE *wag-ina- (source also of Lithuanian vožiu “ro cover with a hollow thing”), from root *wag- “to break, split, bite.” Probably the ancient notion is of a sheath made from a split piece of wood (see sheath). A modern medical word; the Latin word was not used in an anatomical sense in classical times. Anthropological vagina dentata is attested from 1902.