In borderline cases the "pencil test" was used to judge the kinkiness of the individual's hair.

对于一些边缘案例，就用“铅笔测试”来决定他的归属。

youdao

He called those impulses his Dark Passenger, a metaphor that sometimes suggested sexual kinkiness, sometimes drug addiction, sometimes the rage that lies beneath all civilized behavior.

NEWYORKER: Final Cut Pro