Both Uses

Immaculate Conception
in
The Glass Castle
(Edited)

During the sermon, the priest discussed the miracle of Immaculate Conception and the Virgin Birth.
p. 114.6 *

Immaculate Conception = doctrine that Mary was born without original sin
"Baby girl, if your boyfriend ever gets into your panties and you find yourself in a family way, swear that it was Immaculate Conception and start mouthing off about miracles," he said.
p. 114.9

Immaculate Conception = applying the doctrine that Mary was born without original sin in a mistaken way

Definitions:

(1) (Immaculate Conception)
the Roman Catholic doctrine that the Virgin Mary was conceived without any stain of original sin

This is sometimes confused as referencing the conception (biological fertilization of egg) of Jesus. This does not mean Jesus' virgin birth. It refers to Mary's conception (by her parents, traditionally named Joachim and Anne) and says she was specially preserved from sin by God's grace. Catholics celebrate the Feast of the Immaculate Conception on December 8.
(2) (meaning too rare to warrant focus)