Green’s Dictionary of Slang

1. the vagina.

1999		Roger’s Profanisaurus in Viz 98 Oct. 25: smoo n. Austral. A sportsman’s gap; a minge.
2004		L. Redhead Peepshow [ebook] I love the words you guys come up with. Tockley. Smoo. And Cuntox.

2. vaginal secretions.

1986

B. Hudson First Aus. Dict. Vulgarities n.p.: smoo, sexual fluid or secretions [DAUS].