"Although," she adds quickly, "I don't want to promote everybody running around fucking all the time. There are consequences." The stuffy woman nods her agreement.
It was in October 2002, when Sincero was well into her 30s, that she found herself, to her great surprise, having sex with a friend she calls Amanda.
That winter, she found herself wondering if she might be a lesbian. Was that possible? She'd always liked guys, but suddenly she was liking -- really liking -- sex with a woman.
That's when she went looking for a book to explain things. And that's when, after none turned up, she made a pitch to the literary agent she'd landed after writing Don't Sleep With Your Drummer. And that's when she started writing The Straight Girl's Guide.
By the time she was done writing, she and Amanda were done.
And so there's something kind of funny about the way her six-month dabble now defines her. She's the poster girl for bi-curious sex, a title she hopes to parlay into something bigger: A radio show, a sex column, a job as a life coach. It's easy to picture her as a West Coast Carrie Bradshaw, albeit one in rubber flip-flops.
That means Sincero has got to sell Sapphic sex, and sell it she does.
"This has so much to do with empowerment and self-love," she says in her booming voice. "It's about rejecting society's uptight guilt trips! It's really exciting to see people doing what they want do."
But for all her talk of empowerment, Sincero admits that much of the wave she's riding is propelled by male libido.
Many of the girls who come to her workshops, she admits, hope to pick up the skills to pull off a threesome with their man. Traffic on her Web site multiplied by thousands after a phone interview on the Howard Stern Show.
She's convinced, though, that lesbian chic is more than titillation.
"Sure, the only reason it's 'okay' for a lot of girls is that straight guys think it's hot," she says. "That's definitely part of it.
"But what I'm teaching isn't that. These women feel like they have permission to explore it because it's hot -- but then they go do it for themselves and find out they really like it."
Once, Ani Davis kissed a girl, and she liked it. Then she got married and had a baby, and it wasn't until she found herself struggling with post-partum depression that she realized she wanted more.
"My therapist made me realize that I had feelings for women and I needed to explore them," says Davis, a 26-year-old Tempe resident with wide blue eyes.
"You married too young," he told her. "You'll never be happy unless you find yourself."
So while Davis was visiting her family back in Atlanta, she went to a lesbian bar and met a woman.
"We had sex and it was wonderful," she says. "The first time I had sex with a woman, I felt like I was coming home."
She decided she was a lesbian and got divorced, a decision she doesn't regret. But she didn't quite stick with it, either. Not exactly. She found herself unexpectedly falling for a male coworker last year, and after that relationship went bust, she decided she really wanted to date both men and women.
But while she tells men about her bisexual lifestyle -- "That's, like, the opening line," she says, laughing -- she doesn't tell women. She's found that too many lesbians are sick of bi-curious women who want to be "broken in."
"They assume now that if you say you're bisexual, it means you're 90 percent straight but you want to try things, like you want to kiss and mess around with girls," she says. "I want them to know I don't need any training."
Indeed, lesbians say they've been flooded with requests to learn their ways. Shine, a fresh-faced bartender at the lesbian club Ain't Nobody's Bizness, says she gets entreaties from women at least once a month: "I've never done this before, but I think you're hot." (Unfortunately for them, she's got a girlfriend.)
It's been four years since Jessica Stein found herself intrigued by a personal ad from a bisexual woman in the sleeper hit film Kissing Jessica Stein. These days, straight girls aren't stumbling toward their first time with another woman. They're begging for it.
The craigslist Web site in Phoenix draws personal ads virtually every week from women who say they've never been with a woman, but want to give it a try.