Ah, the bizarre tale of Mary Toft's bunny hoax. I know I've blogged about her before, but this story never gets old. This article goes into more detail about how it was achieved.
And so on 27 September, the Tofts cut up a cat, took out its guts and liver, inserted into its intestines the backbone of an eel they had eaten for dinner the previous Sunday, placed the concoction in Mary Toft, and left her alone in the house. She then sent for a neighbor, Mary Gill, complained that she was in great pain, feigned a brief labor, and let her friend hear the monster fall into a pot.