Occasionally I am reminded that some newer kinky people don't know stuff about BDSM culture that I take for granted. Like the Hanky Code.

I read a lot of online forums about BDSM, and I regularly see someone - usually a heterosexual person - talking about how they wish there was some subtle but clear way that BDSM people could signal to each other in public: "Hey, I'm kinky." Hmmm, what about a lapel pin? Or maybe - a necklace? Lots of options are suggested, and then rejected for various reasons.

And I have to smile, because this is a perfect example of reinventing the wheel. As with many sexual things, the gay men got there way ahead of the rest of us and figured all this out. Thus - the hanky code: a color-coded bandanna tucked in the back pocket of a pair of jeans that indicates sexual preferences.

To indicate that someone is wearing a hanky, we speak of them "flagging" and also of "flagging left" or "flagging right." A hanky (or flag) worn in the left back pocket - or in any way on the left half of someone's body - means they are a top. A hanky on the right means they are a bottom.

Sometimes people tie the hankies around their arm, or thread them through the epaulets of a motorcycle jacket. Same principle applies.

You can flag more than one color at a time. However, if you have, say, eleven different hankies hanging off your body, people may think that you're a bit... indiscriminate.

Now, over time, the range of colors listed in various hanky codes has grown to a truly absurd degree. And there are some differences between the gay men's lists and the lists used (although not very much) by lesbians. One sometimes sees some variations regionally, too, although I think the internet has erased a lot of the old East Coast/West Coast differences.

In my opinion, the important ones are: black and gray, which always mean heavy SM and bondage, respectively.

Red is also easy to identify, although for men it means fist-fucking and for women it sometimes means bloodsports, so you're going to want to be clear about that before you go home with someone.

Yellow is a good one. Three guesses what that color is for.

And then there's about a hundred other colors. But if you can tell the difference between "Air Force blue" and robin's egg blue" - especially in a dark bar - well, you've got better color sense than I do. You should definitely ask.

I don't know if there ever was really a time and place where simply wearing a hanky meant someone could just walk up to you and start doing whatever. But that's definitely not what you should do, or expect, now.

It is, however, a perfectly reasonable way to start a conversation with someone at a party - or after exchanging a few significant glances with them in the produce department of the grocery store, for that matter. "Nice hanky. Is that apricot, or orange?"