In Brave New World, what “obscenity” does Linda fling at the DHC?
Chapter Ten features the surprise appearance of Linda, the DHC's former lover, and the even bigger surprise appearance of someone that, up to this point, the DHC never even knew existed: his son. Because of the way in which all fertilisation and birth is done completely scientifically and in test tubes, removing the need of the mother to "bear" the baby and give birth to it, natural pregnancies are something that belong in the realm of the savages in their enclosures. Thus, to be a "mother" or a "father" is akin to an obscenity in this strange world in which Bernard lives. Note what Linda says to the DHC:
You made me have a baby... Yes, a baby--and I was its mother.
The narrator comments that "She flung the obscenity like a challenge into the outraged silence." With these few words, Linda has just managed to completely ruin the reputation of the DHC. Which is of course what Bernard was hoping to achieve.