(transitive, sexuality) To stimulate one's penis between the breasts of (a person).

(idiomatic, vulgar, followed by a wh-clause) I don't know; nobody knows; it is unclear.

(idiomatic, colloquial, vulgar) An expression of anger or frustration.

(vulgar, slang) A person's facial expression during orgasm.

(slang, vulgar) Not quite right mentally: perverted, stupid, or mentally ill.

(Australia, vulgar, slang) Vicious, aggressive, intimidating. / (Australia, Britain, vulgar, slang) Dissuasively or intimidatingly large; massive.

(Australia, vulgar, slang) Excessively

(vulgar, slang, derogatory, Australia, New Zealand, UK) Term of abuse.

Alternative spelling of fuck-knuckle

(vulgar, slang) To actively sexually penetrate someone's mouth; to have vigorous oral sex. / (vulgar, slang) To sexually penetrate someone's eye socket.