n. def. sleeping with your ex-boyfriend or -girlfriend.

XX: Something I've never done myself ... which is not to say that I've never considered it.

XY: Same here. So I guess we're talking about this second-hand. Not that that's so bad. Given the enormity of the sexual pantheon, we're too young to have done everything (and yes, I've got a list ...).

XX: So we've both thought about ex-sex, and we both (I assume) have friends who've done it. It's worked out for the most part for my friends; how about yours?

XY: Again, same here. Which strikes me as curious. It boggles my mind that people who may have once loved each other can so readily divorce the physical aspects of sex with an ex from the emotional ones. And if they can't (as I suspect they can't), then why isn't it messier? Do I have automoton friends? Do they have automoton girlfriends? What gives here?

XX: I guess that we've got a speculative column here, so I'm going to venture an educated guess, as my SAT tutor once advised me. Either someone's hiding an emotional attachment, or these couples can, as you put it, "readily divorce the physical." People hook up all the time for simply physical reasons, and I'm going to say that ex-sex is just one more song in the same key.

XY: Impossible. As surely as "moan" connotes something qualitatively different from"cry," ex-sex, too, is loaded with meaning-

XX: -so it's not messy but it has to be meaningful? I disagree. Also, you assume that all exes "loved" one another. Not all break-ups are bad break-ups-

XY: -first of all, I never said all exes "loved" one another. Second, yes, messy or not, hooking up with an ex is not the same as hooking up with someone else. Finally, if the break-up was "good," then that's all the more reason that it will mean something. If you don't hate your ex, surely sleeping with him will evoke memories of the good times you shared together ...

XX: I guess. But I'd like to point out that even if the break-up is bad, I've had some really good hook-ups with people I really didn't like. Seriously, though, after a year, hasn't it been long enough for the really intense emotions to have dissipated? Is there a time frame after which ex-sex is just plain sex?

XY: Not having done it, I don't think I can really say. But my gut tells me that when it's been long enough for a girl to joke around about how big her new flame's cock is, and for a guy to talk about that great head he got last weekend, you're probably pretty far along.

XX: Are you proposing a litmus test here? I don't know if everyone shares your bizarre sense of humor, but I get your point. So I guess you could say that we're endorsing ex-sex. How fitting.

XY: Well, it's a qualified endorsement. See, I know that ex-sex is a bad idea. Yet I would do it if given the chance. Maybe it's the comfort of being with someone I've been with before, maybe it's that I'd be guaranteed sex (always a good thing) or maybe it's because I would actually be banging someone I love (don't underestimate how different sex is with someone you love)-who knows? Regardless, most of my friends feel the same way.

XX: Just add ex-sex to the list of things we know we shouldn't do, but want to all the same. Like the sixth shot I took on Saturday night: I knew it was a mistake all the way and that I might pay for it later, but boy did it go down easy!