According to Wikipedia, XXX may refer to:

*The number 30 in Roman numerals

Especially applied to:

A year AD or Olympiad (or, by extension, another sporting event) - as in

The year 30 AD

Games of the XXX Olympiad, the 2012 Summer Olympic Games in London, England

Super Bowl XXX, held on January 28, 1996

*A mark indicating "extra strong"

Especially applied to:

Alcoholic beverages

Traditionally applied by brewers to barrels of full-strength beer

A designation for an alcohol concentration in moonshine, sometimes used as a generic depiction of distilled spirits

*Pornography

An identifier for pornography, especially X-rated movies

.xxx, an approved top-level domain intended as a voluntary option for sexually explicit sites on the Internet

Mommy XXX, a porn reality show featuring Demi Delia

Other items, products supposed to be especially strong or effective

A brand of laundry soap in India

*A warning or danger signal

As in

An indication of urgency in radio communication, less urgent than SOS

In computer programming, XXX is a comment to warn other programmers of problematic or misleading code

xxx (usually lower case), as often used at the bottom of affectionate letters or emails

Three kisses, three loving words I love you (each denoted by an x, often used with 'o' to mean a hug: e.g. xox, oxo).

The number 666 in Pythagorean numerology

*And also:

XXX, a 2002 action film starring Vin Diesel

XXX: State of the Union, the 2005 sequel starring Ice Cube

XXX: The Return of Xander Cage, the 2011 sequel of xXx starring Vin Diesel

XXX (album), a 1999 album by the rock band ZZ Top

XXX: Exklusibong, Explosibong, Exposé, a Philippine current affairs television show

XXX, the ISO 4217 currency code for "no currency"

ArXiv.org e-print archive, formerly known as xxx.lanl.gov

XXX Cantos, a poem by Ezra Pound

A symbol of the straight edge lifestyle

A shortened version of "XXXL", a plus size clothing size

A reference to Amsterdam, after the three crosses on the Coat of arms of Amsterdam

A flavor of Vitamin Water

Agent XXX, the code name for Anya Amasova, a fictional character in the James Bond franchise