eccentricity; peculiarity; strange hobby

mysophobia; obsession with cleanliness; extreme fastidiousness

sexual fetish

bad habit

addiction

onychophagia (nail biting)

transvestism

pica (medicine)

necrophilia

(sexual) fetishism

pedophilia

foot fetish

foot fetish

sadism (fetish)

exhibitionism

indecent exposure; flashing

lit. cut sleeve (idiom); fig. euphemism for homosexuality, originating from History of Western Han 漢書|汉书: emperor Han Aidi (real name Liu Xin) was in bed with his lover Dong Xian, and had to attend a court audience that morning. Not wishing to awaken Dong Xian, who was sleeping with his head resting on the emperor's long robe sleeve, Aidi used a knife to cut off the lower half of his sleeve.

moral fastidiousness; psychological obsession with maintaining moral purity in thoughts, relationships etc