When it comes to penis size, the politically correct party line is "size doesn't matter." But let's get real, shall we? Even tampons are available in junior, regular, and super sizes, and some women (myself included) are the proud owners of dildos (a sex toy used for vaginal or anal penetration), in sizes ranging from diminutive to gargantuan.

The truth is that size matters, but not necessarily in the way you might think.

It's not that bigger is necessarily better, but that different sized or shaped phalluses can stimulate a woman's vagina in different ways.

But first, a little about me. I'm a lesbian sexpert and author of The Whole Lesbian Sex Book. Now, you're probably thinking, who am I to be telling guys how to please a woman through intercourse? Admittedly, I have little sexual experience with men. But as a lesbian, I have an abundance of experience in pleasing woman through penetrative sex (that's where those dildos come in handy). And I've had quite a bit of experience talking with my male friends about sex with women.

Magical Mystery Tour Before we get to the "use what you've got" lessons, let's begin with an anatomy tour of the vagina. The opening of the vagina sits below the clitoris (the most sensitive area on a woman's body; most women require direct clitoral stimulation to reach orgasm) and the urethral opening, and above the perineum and anus. The vagina is made up of very elastic tissue that opens up and expands during arousal (and childbirth). When a woman is not aroused, the walls of her vagina touch. Contrary to what you might think, girls do not have a big "hole" in there.

The vagina isn't a passive receptacle, either. The opening of the vagina is quite muscular and will contract with pleasure when stimulated, gripping a penis or finger.

The outer third of the vagina contains the most nerve endings, and most women find it to be more sensitive than the deeper areas of the vagina. The opening and G-spot are responsive to a range of touches; the deeper areas are more responsive to pressure or thrusting.

Thus a small or slender penis may produce deliciously subtle sensations in the sensitive areas of the vaginal opening and G-spot, while a long or thick penis may offer a woman more of a sense of fullness.

The G-Spot The G-spot isn't a magic button, but rather an area of tissue that feels a bit rougher in texture than the rest of the vagina walls. You can thrust into a woman's G-spot during intercourse, but fingers are really well suited to the job of G-spot play. Find your partner's G-spot by inserting two fingers into her vagina and making a "come hither" motion, pressing toward the front of her vagina.

Rhymes With Dolores The clitoris is hardly just the little nub of flesh hiding in the folds of the labia. That's just the tip of the iceberg, so to speak. The clitoris is a complex structure of erectile tissue, much of which extends into the vaginal walls. So thrusting against that vaginal tissue, particularly in the areas nearest the opening, provides a woman indirect clitoral stimulation. For women whose equipment is very sensitive or who simply love clitoral penetration, that's enough to send them over the edge.

At Your Cervix The vagina ends in the cervix, the knob-like opening to the uterus through which menstrual blood exits. With deep thrusting, an average length penis will probably reach the cervix; a long penis will definitely hit the mark. Some women love to have their cervix pounded; others hate it. Ask your partner what she likes, and if you're hung like the proverbial horse, be careful not to bruise or abrade your partner's cervix.

Different Strokes A long, skinny penis isn't better than a short, thick one, and a humongous erection doesn't trump them all. But a girl's got a right to a preference. The important thing is that each woman you bed will have different experiences, desires, and responses in regard to penetrative sex. One may like deep, full thrusting. Another might want it fast and hard and not care where or how deep your penis reaches as long as you keep up that rhythm (and most certainly hold off coming for a long time). Another woman may even prefer anal penetration to vaginal penetration; for her, a smaller penis may take the prize.

So, what's a guy to do? Unless you've got a collection of dildos, you probably only have one phallus in your collection -- the one you were born with. Not to fear. In a future article, I'll offer you some tips on making the most out of what you've got.