To survive he must chow down on the same food as the other Van Daams, embalmed corpses. Unfortunately the only suitable entree Dr. Marlowe has on hand is a pickled baby. So he eats it. Imbued with a newfound lust for life he has passionate sex with Kathleen, she is so tickled by the attention as not to notice her husband's fetus breath. During the chaos of freaks attacking and the floor collapsing John realizes that he doesn't want to live in the world of normal humans, he wants to live with the other Van Daams.
Incest is a symptom of narcissism.
Formaldehyde is a poor substitute for perfume. Women love pasty faced men with mismatched eyes and feeble constitutions. There is a direct connection between hermaphrodites and alcoholism. Skeletons always remain in one piece. Pickled babies are an aphrodisiac.