Enter the Clowns (2002)

When Xiao Bo's trans mother, who transitioned and wants to be called mom, is dying, she insists on having the taste of Xiao's milk (sperm) when she dies, so he gives him head. Soon after, he meets his best friend, Nana, for the first time after her transition, now a beautiful woman. Other acquaintances transition while Xiao copes with his loss. Nana becomes despondent at the prospect of never finding the right man.