Enter the Clowns (2002)

Xiao Bo lives in a world where the lines defining men from women are constantly dissolving. He kneels at the deathbed of his father who has become a woman, and whose dying wish is to have oral sex with his/her son. His boyfriend Nana has also undergone a sex change, but Xiao Bo no longer finds her attractive as a woman. A sexual chain reaction ensues that wreaks havoc on traditional Chinese roles that govern male and female, parent and child.