A vagina. This is where a penis would normally be inserted (although there are other points of insertion). In other cases, it is where a woman inserts her vibrator, or where someone inserts their tongue, or fingers, etc. Lots of things can go up there, but they're all working towards the same goal.
A.K.A---Bearded Clam(my personal favorite), Taco, pussy, cunt (just to name a few).
"I want you in my cooch!"