It's not news that sexual fluidity has been working its way into the mainstream. We all know the girl who experimented in college and then went back to guys, or the middle-aged woman who left her husband for some turquoise artisan in Taos named Deborah.

Both seem to be examples of the stronger sexual preference winning out in the end. But more and more, it's becoming acceptable for women to "hop the fence" -- that is, to make the occasional gender switch-up in casual sex and in long-term relationships. I know, 'cause I'm one of 'em.

Although I'd always privately identified as bisexual, I'd only dated boys before I met a girl I had instant chemistry with. We had an amazing, insanely sexy couple of months, but we wanted different things out of a partner, and things fizzled in the natural way romantic relationships of either persuasion do.

The next person I dated happened to be a guy, and it was wildly irritating when my parents and friends -- who had been supportive of my dating a girl, if dubious -- acted vindicated. I wasn't bisexual, they thought -- I was just going through a phase. When I dated another girl a year later, they were more respectful of the fact that it was an actual relationship. This, apparently, was how it was going to be.

More and more of us are deciding to shirk traditional definitions of sexuality in favor of doing what feels natural. We all know a girl who says she's always been attracted to other women but has never really done anything about it, save the occasional bar make-out or session spent watching girl-on-girl porn. So why don't more women act on it?

I'm Bisexual. No, Really.
First, I think there's a stigma attached to bisexuality. Sure, I got a lot of flak from my friends ("Oh, having the obligatory lesbian fling? How second-season-of-'The-O.C.'") and my parents ("But you've always liked boys! Is this because we sent you to art school?"), but I also got a surprising amount of stink-eye from my girlfriend's lesbian friends.

A lot of the GLBT community is kind of dismissive of the "B" element. My girlfriend identified as strictly lesbian, and most of her friends thought of me as some kind of sexual interloper. (Many lesbians will patently not date bisexual girls, which I find ridiculous.) I get that lesbians have had to struggle with discrimination and oppression as both women and homosexuals (I get it, guys, I really do!), but the fact that I also like to date men doesn't make my love for -- or attraction to -- a woman any less real. I like penises and vaginas -- if you don't want me to be part of your culture because you think I'm some sort of sexual dilettante, fine. You go enjoy Lilith Fair, and I'll enjoy hot sex with my girlfriend.

Do the (Fairly Simple) Math

Reason Two why so many girls remain "untested bis"? Sheer numbers and availability. I date guys more often, but that's because I don't specifically seek out gay bars. While flirting it up in a bar with a member of the opposite sex is fairly normal, it can be hard to tell if that cute girl at my favorite watering hole is gay (unless she's wearing a Michfest T-shirt). So unless I get an introduction from a mutual friend who knows I'm into girls, I'm unlikely to just randomly meet a chick in the same way I might a guy.

If you factor in that the majority of the population identifies as heterosexual, you're working with a much smaller pool of potential "les" dates. So even though it's sheer mathematical probability that leads to my dating men most often, I still end up getting accused of being a fauxsbian.

I Don't Know What to Do With My Hands!
When I first started dating girls, I was amazed at how many friends boozily confided in me that they harbored secret same-sex curiosity. The biggest thing keeping them from acting? "Hey, uh, how do lesbians have sex?"

"I'm totally into breasts," confided one friend, "but I'd be terrified to go down on a girl."

Honestly? It's a little scary at first. But it's the same as heterosexual sex: You're nervous for the first time, but you get over it pretty quickly, because at some point, it feels f**king great. It's sex! You'd be surprised how intuitive it is. So many girls approach being with a woman with the same trepidation as assembling a particularly tricky piece of Ikea furniture. Ever had a guy go down on you or finger you? It's pretty much the same deal, just with less chest hair and more toy involvement. Not to mention with somebody who actually knows her way around a vagina.

It's different than being with a guy, sure, because usually hetero sex has a clear stopping point: when the guy comes. As another girl who dates both men and women put it, "In my experience, girl-on-girl goes on indefinitely. This can lead to faking -- and guess what? Yes, we can fake, even if it's with another lady! On the plus side, it's really nice to not walk away with beard burn."

I'm on the Fence, and That's the Way I Like It

I'm currently not in a relationship, and I'm not sure whether I'll date a man or a woman next (and yes, I've enjoyed casual flings with both). The point is, I'm not actively looking for one or the other.

I could say that I'm not attracted to the gender, I'm attracted to the person -- but that would be a lie. While I'd love to meet somebody hilarious who loves Coen brothers movies, bourbon and PBS, sometimes I just like the way your ass looks in those jeans -- regardless of your gender.

Beth Brennan is the pseudonym used by Lemondrop bloggers and contributors when we want to write naughty stuff but keep our jobs/boyfriends/girlfriends/dignity. You can email her here.