Imagine that you hear that your 18-year-old daughter was kissing another girl at a party last weekend. What races through your mind? "O my gosh, she's exploring same-sex attractions. She must be a lesbian."

Hold up, Mom and Dad. You're showing your age. Chances are, your daughter's not fixed on the pretty young blonde she's locking lips with. There may be something entirely different and unexpected going on.

"Girls making out with each other to turn on guys is the latest craze at high school and college parties," according to the online magazine Salon.com.

Still don't believe it? Listen to this summer's monster hit song, "I Kissed a Girl" by Katy Perry. It's an international phenomenon -- topping the charts all summer in America, Canada, Australia and Great Britain. A few weeks ago, Perry was a headliner at the Warped music festival at Canterbury Park in Shakopee, belting out the song's provocative lyrics:

I kissed a girl and I liked it,

The taste of her cherry chapstick,

I kissed a girl just to try it,

I hope my boyfriend don't mind it.

It felt so wrong, it felt so right.

Perry cagily maintains that her song is about drunken curiosity regarding same-sex attractions. But her music video, which features gyrating women in lingerie, is clearly designed to give the male libido a jolt.

We baby boomers like to think we invented and defined the sexual revolution. But our offspring are tossing out the categories we took for granted, including the view that "gay or straight" is preprogrammed.

Young women whom Salon.com interviewed about the girl-on-girl trend said they had initially kissed other females to get a free beer at parties or on a dare from guys. But they soon saw it as a way to signal to males that they are "sexually open and adventurous."

"It was like, look, I'm the center of attention!" recalled one 16-year-old.

The 16-year-old, who first saw girls making out at a party and later tried it herself at male urging, added, "And the kissing itself didn't really bug me. From then on, it became a normal thing to do."

"It makes you feel more attractive," said another girl. "You're turning on a guy, and he thinks it's cool."

Staged bisexuality is now the norm for what is being called the "post-gay generation."

Salon reports that "the term for the 'I'm straight but I'll kiss girls' mentality is 'heteroflexible,'" according to Deborah Tolman of (where else?) San Francisco State University's Center for Research on Gender and Sexuality. Salon also has its headquarters in San Francisco.

'The erotic new trend'

Female bisexuality is "the erotic new trend (everyone's trying it)," announced Marie Claire magazine in 2006.

A 2005 survey by the Centers for Disease Control and Prevention appeared to confirm this. It found that while 1.3 percent of women identified themselves as homosexual, 11.5 percent of women ages 18 to 44 -- and about 14 percent of women in their late teens and early 20s -- report at least one sexual encounter with another woman.

Only about 4 percent of women, ages 18 to 59, reported such an encounter in a similar survey in 1992.

What is fueling this trend?

One factor is the huge popularity of Girls Gone Wild, a DVD franchise that films alcohol-addled females' sexual encounters with other women at college drinking revels. Same-sex kissing has been glamorized by celebrities, including Madonna and Britney Spears.

One of the biggest influences, however, may be Internet pornography, which has dramatically altered young people's ideas of mainstream sexual behavior.

"Girls aren't kissing other girls because they want to," Pamela Paul, the author of "Pornified," told Salon. "They're doing it because they want to appeal to boys their age. And for boys their age who've developed sexually alongside Internet porn, their sexual cues are affected by the norms and standards of porn. And that's girl-on-girl action."

The result? Rampant cultural confusion.

Straight girls 'playing gay'

Chicago Tribune sex columnist Jenni Spinner, who is a lesbian, maintains that Perry's "I Kissed a Girl" song "sets gay rights back." In nearly every "gay dance dive," she has complained, "the joint has been infiltrated by a gaggle of giggling straight girls, playing gay for a night because it amuses them."

Women who kiss other women to attract guys are making it "difficult to distinguish between the behavior of someone who is legitimately sexually interested and someone who wants to impress the boy across the room," according to New York magazine.

Increasingly, young people are transcending sexual categories altogether, the magazine points out. They are coining terms such as "pansexual," "bi-curious," "bi-queer" and "metroflexible" to describe their fluid sexuality.

This is the brave new world that the sexual revolution unleashed. Has it liberated our daughters, as originally promised?

One young woman interviewed by Salon says that, for her and her friends, it comes back to an age-old desire to be cherished by a man.

"A lot of girls who do want long-term boyfriends will still settle for the hookup [triggered by girl-on-girl kissing] because it gives them that temporary feeling of being taken care of and being close to someone," she said.

"It's sad to see that this is what it's come to -- that guys will raise the bar and girls will scramble to meet it. Women just want to know what they have to do to get these guys to fall in love with them."

Katherine Kersten • kkersten@startribune.com Join the conversation at my blog, www.startribune.com/thinkagain.