What’s the origin of “XXX,” as in porn movies and booze?

A STAFF REPORT FROM THE STRAIGHT DOPE SCIENCE ADVISORY BOARD

Dear Straight Dope:

What is the etymology of the 'XXX' symbol used to represent spirituous beverages in a host of cheesy movies and books? And why also the use of the same symbol to represent sexually explicit material? Are the two uses of the same symbol somehow related?

Lar replies:

Approximately 600 pounds of assorted reference books, and the two I keep coming back to are Joy of Cooking and Brewer’s Dictionary of Phrase & Fable. How depressing.

Brewer’s has this to offer on the origin of XXX: “X on beer casks formerly indicated beer which had paid the old 10s. duty, and hence came to mean beer of a given quality. Two or three crosses are mere trademarks intended to convey an impression of its extra strength.”

Our online dictionary gives a definition of X-rated (adjective) and indicates that it first came into use in the 1970’s but doesn’t draw any parallels between alcohol and sex, which has got to be a first in the history of mankind. It seems logical to conclude that the purveyors of smut borrowed the ‘the more X’s the stronger it is” tradition to give your average Joe (god help me, I almost said Joe Blow) the clue that he was about to view some extremely juicy stuff.

Send questions to Cecil via cecil@straightdope.com.

STAFF REPORTS ARE WRITTEN BY THE STRAIGHT DOPE SCIENCE ADVISORY BOARD, CECIL'S ONLINE AUXILIARY. THOUGH THE SDSAB DOES ITS BEST, THESE COLUMNS ARE EDITED BY ED ZOTTI, NOT CECIL, SO ACCURACYWISE YOU'D BETTER KEEP YOUR FINGERS CROSSED.

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