Stay at Carla's for a while yet.

"Why don't we stay here for a bit? It's not too loud and there's plenty to drink. The dance doesn't start for a while yet and perhaps the queues for the photos won't be so long towards the end of the night," you decide after a moment of thought.
Katherine readily agrees with your idea. "Sure, sounds like a good idea. Do you mind if we go inside the house? It's getting kinda cool out here."
"Of course we can. You must be getting cold in that dress," you say as the two of you get up and move inside.
"Yeah, it's is a little chilly alright. I was fine before, but it got cold all of a sudden when the sun went down."
You slip your jacket off your shoulders and offer the garment to Katherine. "Here why don't you wear this," you say.
"Thanks a lot," Katherine says as she takes it and puts it on, holding it close to herself.

You stop to grab more to drink from the kitchen before heading to the lounge to take a seat. The room is filled with other people dressed up and ready for the dance. You and Katherine start talking and you're so engrossed in what each other has to say that unnoticed to you both, the room slowly empties of the crowd. It's not until the last guest has gone and Carla comes up to you two that you realize that you're all alone.
"Hey there. Everyone's gone to the school now, so I'm about to leave myself. You guys can stay here if you like. Here are my keys Kat. Just leave them under the doormat when you head off," Carla says giving her house keys to Katherine.
"Okay, no worries Carla. Thanks for letting us stay. We were having such a good time talking that we did not even notice anyone go," Kat says as she puts the key ring inside her little matching black purse.
"Seeya then," Carla says to you both as she goes to the door.
"Bye," Katherine and you echo as she leaves.

The house is now empty besides the pair of you. Katherine gets up and goes to the stereo. She starts to look through the great pile of CDs. "Could you grab me another drink from the kitchen while I put something a bit better on? You get the drink and by the time you return, she has found a Blur album and is playing that.
"Nice choice," you say as you hand her the drink. She has been drinking vodka and cranberry juice all night and you deliberately man this one a touch stronger than the others. She takes it and has a small sip before a mischievous twinkle comes to her eye.
"Hey, do you want to have a bit of an exploration through the house? I'm sure we could find some cool stuff in Carla's room," she says as she pulls you off to where Carla's room is situated.

Carla's room is much like all the other girls' rooms you have seen. Posters line the walls and you can see a heap of stuffed toys on top of the chest of draws. You feel you have to protest at what Katherine is doing. "I'm not sure we should be doing this Kat."
"Oh, it's fine. Girls always do this. I'll tell her I was looking for something warmer to wear. Besides I've caught her going through my lingerie draw before," Katherine says dismissing your concerns. She holds up various bits of skimpy underwear she's found for you to see. You have to admit that imagining Carla in some of the see-through bras and thongs is quite a turn-on. It's then that Katherine exclaims, "Oh my God! Check this out."