That little organ

One little organ, as big as a fist.

Oh how great, as it shelters fetus.
It bleeds monthly, and contracts badly.
Oh how joyous, as it grows a person.
A woman's joy, but it brings pain.
Hollow little organ, uterus by its name.
That little organ, wonderful creation.

P/S: Just found the pantie interesting, not mine by the way. Haha.