The vagina has the equivalent of the coronal ridge hook.  Medically, it's called the carina.


It could just as easily be called the carinal hook.

Because, when the natural penis withdraws on the outstroke, the carinal hook captures the foreskin.

As does the coronal hook.  

The foreskin gets penned in between the carinal hook and the coronal hook,


   causing the foreskin
   to bunch up.


During intercourse, as the penis thrusts in and out, the foreskin continually bunches and unbunches against the roof of the vagina.


For the woman, the rhythmic bunching & unbunching
of the foreskin during intercourse creates sexual excitement by alternately applying and releasing pressure against the highly erotic G-spot in the roof
of the vagina that triggers orgasmic pleasure.





IN SUMMARY: The foreskin is a natural gliding stimulator of the vaginal walls during intercourse, increasing a woman's overall sensual excitation
and helping her to achieve orgasm more easily and more often.