Eroticism is in the eye of the beholder. In Japan, some women turn to electrically charged squid for sexual satisfaction. In the American world of masochism, one man begged to be tied on a spit and roasted over sizzling coals. His counterpart, a latex-loving dominatrix, reached ecstasy merely watching his pain.
What is abnormal may not necessarily be unnatural, according to sexologists who study the outer limits of the human psyche.
And, increasingly, as seen in a plethora of new books and films -- not to mention thousands of sites on the Internet -- kinky sex is getting more attention.
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"To badly paraphrase Alfred Kinsey, [who pioneered sex research in the 1940s and 50s, filming couples in flagrante in his Indiana attic], 'the only unnatural sex act is the one you can't perform,'" said Robert Dunlap, a California sex therapist and filmmaker.
Paraphilias -- or socially unacceptable sexual practices -- are more common than most ordinary "vanilla" teleiophiles [those who desire adults] would imagine, according to Dr. Judy Kariansky, a sex therapist from Columbia University.
Though there is no hard data on what whether a spike in interest means a spike in actual activity, experts say anecdotally that couples are showing a marked interest in exploring new sexual intensity.
In his 2001 film, "Beyond Vanilla," Dunlap interviewed more than 200 subjects who had one common denominator, some type of fetish -- bondage, flogging, knife play and fire, among others.
When asked "What is kinky?" academics, doctors, lawyers and even a congressman, shared fantasies like, "sex with a taxi driver in the back seat," "pouring candle wax on his testicles," "arresting someone and patting them down on the bar," "being gang-raped by many sets of twins, or better yet, triplets."
The film was widely praised and used by the University of Minnesota medical department at conferences on human sexuality and development.
Today, Dunlap is in negotiations for release of his latest film, a biography of the life of Xaviera Hollander, the madam who brought kinky sex out of the closet in 1971 with her book, "The Happy Hooker." His documentary earned early acclaim at numerous film festivals.
Also out this year are two books that appeal to those interested in sex outside the normal boundaries and that explore a world where pain, pleasure and often guilt intertwine.
One, "The Other Side of Desire," is a journalist's exploration of "the far realms of lusting and longing," including that reference to the pain aficionado who ordered her "servants" to barbecue her willing submissive.
Another, "The Adventurous Lover," which is part of the new "Joy of Sex" series, is a handbook for couples who want to experiment in a safe environment.
"It's a totally new revolution and it's really exploded," Dunlap told ABCNews.com. "The Internet has changed everything. So many people can go online and say, 'This is me. I love this. I am finding like types.'"
And for those who think this phenomenon might encourage anti-social behavior, he counters, "I don't think anyone was really damaged or hurt by book or movie."
Columbia's Kuriansky agrees that "what's weird, sick or kinky for you is what practitioners defend as 'normal' for them."