XXXX · noun1
From the (Australian) XXXX brand of lager, which was named after the practice of using repetitions of X, such as XXX, to indicate the strength of an alcoholic beverage, and which was advertised with the slogan "Australians couldn't give a XXXX for any other lager."
XXXX · proper noun2
From X chromosome.
XXXX · adjective3
From X (“motion picture "adult" rating”).
Etymology from Wiktionary, CC BY-SA 4.0.