Gay refers to a male individual whose sexual orientation is homosexual (sexually attracted to other males). Although it is sometimes used as a blanket term for homosexual people, a female who is sexually attracted to another female is usually referred to as a lesbian.
Beginning in the late 1960's and continuing until the early 1980's, gay men would signify to one another that they were gay by wearing an earring in their right ear. This practice faded away during the 1980's as piercing became more and more popular with both gay and straight men who began piercing not just one but, in many cases, both ears so that today the distinction is essentially meaningless.
Similarly, in the general population both in the U.S. and other westernized nations, no special significance as to sexual orientation or sexual proclivities is given to either men or women solely based upon the fact that they are pierced or tattooed on any particular part of the body. Thus, you can safely choose to be tattooed or pierced with little concern that such modifications alone will identify you as gay or lesbian or that they will signal to general observers your sexual interests.
If, you present yourself as gay or lesbian or if you venture into a social setting of gays and/or lesbians, like visiting a gay bar, attending a gay pride celebration or similar events, your tattoos and/or piercings will be perceived by some, but not necessarily all, as having special significance. Both tattooing and piercing can signify certain sexual preferences in the gay and lesbian community, especially within certain subcultures, like leather. Members or participants of certain fetish subcultures like bondage and discipline (B&D) or sadism and masochism (S&M), whether gay or straight, may also ascribe meanings to particular body modifications but are unlikely to assume such unless you otherwise provide verbal and/or non-verbal cues (the way you dress) that you are a member of that group.
Among gay men, piercing the left nipple only or tattooing an armband on the left upper arm only, can be perceived as a statement that the wearer is a top or dominant, meaning that sexually he is anally insertive and orally passive. In the context of someone who is into B&D or S&M, it means that they are the dominant partner in sexual activities and function as the master, daddy or sir.
A gay man who has pierced his right nipple only or has tattooed an armband on only his right upper arm, can be perceived as the bottom or submissive, meaning that sexually he is the anally receptive partner and orally active (. In the B&D and S&M subculture, it means that they are the submissive partner in sex, and function as the slave or boy.
Leather women and lesbians who practice B&D and/or S&M may also use the left/right placement of jewelry or tattooing as well to signify top/bottom and dominant/submissive roles. This may also be reflected in women by the wearing of a larger earring/piercing in the left ear or nipple than is worn in the right, or multiple piercings in the left ear or nipple as opposed to a single piercing in the right to signify the top/dominant role.
Among heterosexuals (in the B&D and S&M subcultures, piercing and tattooing can have the same significance in identifying both dominant and submissive roles.
It must be noted that the significance of wearing a piercing or tattoo on the left or right side of the body described above is not universally understood within the gay and lesbian community. As tattooing and piercing have become more mainstream, both are as likely to connote to many a mere fashion statement as they are to indicate the sexual role one may play with a sex partner. However, if you choose to so modify your body and participate in the leather, (B&D) or S&M subcultures, many will understand your piercing or tattoo to reflect such preferences.
While neither tattooing nor piercing are in and of themselves gay, the popularization of piercing and tattooing has very strong roots in the gay community. Gay men were at the forefront of adopting and incorporating piercing into their fetish wear and making piercing a part of sexual play.
Similarly, during the renaissance of tattooing that occurred from the late 1960's on, gay men were some of the first to embrace the concept of the full-body tattoo a radical body-modification in the era before the mid-1980's. Don Ed Hardy, perhaps the tattoo artist most responsible for the merging of the traditional Japanese full-body tattoo with Americanized iconography—including overtly homoerotic imagery—made his home in San Francisco during the 1970's and 80's where his radical tattoo work was strongly embraced by both the gay and fetish communities. And, while Hardy worked in San Francisco, Cliff Raven, a tattoo artist and an openly gay man himself, expanded the idea of what tattooing could be at his legendary Sunset Strip Tattoo Studio in West Hollywood, California where he was responsible for large-scale traditional Japanese influenced work on many gay men.
Today, tattooing and piercing literally cuts across all demographic groups making it more true than ever that "You can't judge a book by its cover."