The Sisters of Perpetual Indulgence (SPI), also called Order of Perpetual Indulgence (OPI) is a charity, protest, and street performance organization that uses drag and religious imagery to call attention to sexual intolerance and satirize issues of gender and morality. At their inception in 1979, a small group of gay men in San Francisco began wearing the attire of nuns in visible situations using high camp to draw attention to social conflicts and problems in the Castro District.

The Sisters have grown throughout the U.S. and are currently organized as an international network of orders, which are mostly non-profit charity organizations that raise money for AIDS, LGBT-related causes, and mainstream community service organizations, while promoting safer sex and educating others about the harmful effects of drug use and other risky behaviors. In San Francisco alone where they continue to be the most active, between 1979 and 2007 the Sisters are credited with raising over $1 million for various causes, or almost $40,000 on average per year.[

https://en.wikipedia.org/wiki/Sisters_of_Perpetual_Indulgence

see also: http://www.universaljoy.com.au/