Sex and Zen III (1998)

The plot follows new prostitutes Susan (Karen Yeung), Fanny (Tung Yi), and Chinyun (Chung Chun), who are inducted into the Fragrance House brothel where they are trained in the ways of lovemaking by their veteran madam Tall Kau. Eventually all three enter circulation where Susan is crowned the top prize and becomes enamored of budding scholar Chu Chi-Ang. Fanny is jealous beyond all means and though she’s bought by famous horse trader Sir Lui (Category 3 staple Tsui Kam-Kong), she still plans her revenge on Susan. Eventually the typical “torture the innocent naked girl for cheap thrills” stuff happens, while Chu learns various wacky sexual positions to get Susan back.