"...I'm not really into anal stuff."

Katie says, sounding very reasonable. You, of course, know this about her. As it does in most modern relationships, you'd imagine, the question came up early in your relationship when you were experimenting with all sorts of dirty things, positions, ideas; discovering each other's turn-ons. Katie said that she'd tried it once and it wasn't for her. You never pressed the issue since then. You didn't need to. There's been plenty of other stuff to do.

But Karen isn't having it. "Are you crazy?" She asks. "Are you Mormon or something?"

Katie laughs. She's staying positive. "No. It's just not my thing."

Karen lets out a big sigh. "Let me guess. Some boyfriend you had in college who was a real asshole, but you didn't know it at the time said you should do it because it would be really hot and you agreed and instead of properly lubing up he spit on his cock or something like he saw in a porno and it was terribly uncomfortable and because of that one stupid experience with that one stupid guy you've been missing out on the most amazing physical pleasure ever since."

Katie's eyes pop open, and then gloss over in contemplation. You sense that Karen isn't really that far off the mark. You also realize that she must be one hell of a lawyer. Even several drinks into the evening (or is it morning, by now?) she's making a convincing case.

"You know what you need?" Karen asks, perhaps sensing that she's starting to convince Katie. "You need a starter toy. You need something a little smaller."

Katie just looks at you. You know that look. She's considering it. You try to wrap your head around what's happening... all of it. The toys, the wine, Karen's "guy-sharing" comment, Katie's sudden interest in buying what Karen is selling.

Your neighbor rises and heads toward the stairs next to Katie. As she passes your girlfriend she places a hand on her shoulder. The physical contact it's unexpected. It's unexpected to you as a viewer, and you can tell that it's unexpected, though not unwelcome to Katie.

Then Karen leaps up the stairs with excitement and with a tipsy thud, falls down.

Katie jumps up and runs toward her. You stand as well and start to walk over.

Karen seems fine, no worse for wear. But she's lying on the stairs now. Katie kneels in front of her. "Are you okay?" She asks with a giggle, probably sensing that she's just fine, maybe a little embarrassed.

But you wonder if they notice how close their faces have gotten; how Katie is practically on top of Karen as she reaches over and attempts to help her up.

Well, Karen certainly has noticed. She reaches back, wraps her hands around your girlfriend's back and lunges forward, pressing her lips against Katie's.

You stop walking. Are you really seeing this?

Has Karen's sexual aggression finally gone too far? You're really not sure how Katie would feel about this. But you get your answer as you see your girlfriend's tongue gently push itself into your neighbor's mouth.

And they kiss. A long, sensual kiss. Karen's hands trail down Katie's hips and grab her ass. This is surreal.

You watch. You just watch. And grow erect.

Finally they pull their lips apart. You expect Katie to glance over at you as she does at times like these. But she just stares at Karen's face. She's entranced by your neighbor. "What happened to 'guy sharing'?" she asks with the type of smirk you've seen on her face when she's feeling horny.

"Girl sharing is fun too." Karen says, as if she's quite familiar with it. "Come upstairs with me." She whispers loudly. "I have fun stuff upstairs. We can..."

"Okay." Katie answers, not wait for her turn to talk.

And then Karen glances at you.