>>29159359Chinese population skews pretty heavily male overall, and tends fairly sexually conservative - thus generating a lot of sexual taboos. The reason for the male skewed population is because women aren't valued as highly as men, and the now defunct "One child" population control policy meant that many couples would simply abort when a female fetus began to develop.
Sexual taboos, general sex negativity, and negativity towards homosexuality; Sex drive is something you're going to have regardless of how positive or negative your view of sex; however adopting sex negative views typically just make you find bad things sexually enticing - conservative racists are the primary consumers of BBC porn; homophobic politicians/priests getting outed by gay prostitutes, etc.)
In the case of China, a negative view of sex, homosexuality, and women - a number of males become attracted to the idea of playing a feminine sex role. Because eastern cultures are often more civically or collectively minded, the violation of civic expectation via public exhibition (flaunting of cultural taboos regarding sex, women, gay shit, and orderly public behavior) would become a likely common set of kinks.
A highly competitive mating pool owing to a generation of excess males, causes men to be more flexible with what we're willing to cram out dicks into - but pair this with a cultural tendency to avoid or ignore when even flagrant violations of social order occur (in an attempt to avoid worsening the perceived violation, if one is not working in a role of maintaining social order.) you have a background cultural cycle that unintentionally reinforces the behavior of the taboo-breaker by either ignoring it and allowing it to occur - or rewarding the behavior by giving the taboo-breaker exactly what they want.
I don't have a ton of science to back this, but it makes intuitive sense if you know anything about sexuality. It also makes me rock fucking hard but I'd never do it for fear of AIDS.