I'm guessing, based on the other stuff in the book, that certain people... I don't want to call them vulgar... took an existing term and gave it a more subversive... I don't want to say vulgar... meaning. I mean, that's usually the case in the book. Occasionally there are original words or phrases but a lot of times they're just adaptations of existing words.
OED does not list tussy-mussy, but it does list tussy: "A cluster, posy, or knot of flowers or leaves; an ornament of silver or gold of this form, forming a buckle or the like."
OED, interestingly, lists tuzzy-muzzy as the main spelling and tussie-mussie as a modern variant: "A bunch or posy of flowers, a nosegay; a garland of flowers. Also fig. Revived in 20th cent., usu. in form tussie-mussie."
Additional meanings: "As popular name of particular plants or flowers (see quots.); also, a bur." "Dishevelled, ragged; fuzzy. dial."
And the third meaning (I post them here out of order): "See quots. slang. Obs. 1711 E. WARD Quix. I. 70 And Salt as Lot's Wife's Tuzzy~muzzy. 1721 BAILEY, Tuzzimuzzy,..a jocular Name for the Pudendum Muliebre.Hence in HALLIWELL, and in later Dicts."
It offers 9 usage examples of the first definition (beginning in 1440!) before the date of the 1st usage of it as a vulgar term in 1711.