Too Busy Freaking out

"FUCK!" I screamed, panicked, pulling my still hard dick out of her tight pussy, looking down and seeing a fairly substantial amount of my jizz slosh out as I did, then still more slowly begin to leak out of her as she lay there. "FUCK, I came in you! Are you on birth control?"

"No, but why are you worried?" she replied, giving me another perplexed look. "You said you didn't want me to get pregnant," she added, shifting up onto her elbows to face me more directly, in the process presenting her tits to me like it was no big deal. "Did you change your mind? If you want to use me to have your kid after all, your cum is still in there. I could get pregnant right away," she added in the most matter of fact, do-you-want-a-perfectly-normal-favor-from-your-sister tone of voice.

"WHAT!!! NO NO! That's crazy," I screamed back, and my dick finally got the message and went soft. I sat there hyperventilating for a second, as she made no move to deal with the cum still leaking out of her.

"Are you done using me for now, bro?" she asked after what felt like hours but was probably only a few seconds, again as if it was no big deal, though I could swear I saw her eyes roll a little, as if I was the one being weird and she had to deal with it.

"Are you serious right now?" I replied incredulously.

"Did you not pay attention in sex ed?" Amy asked bluntly.

"Did YOU?" I countered defensively. "The big lesson I remember: Cum in pussy means pregnancy, so use a condom or at least pull out."

"You are using me. You said you didn't want me to get you pregnant. You can use me however you want, so if you say no to pregnancy, that means no pregnancy! See, I was paying attention, unlike someone who appears to have dozed off," she said with an exasperated expression. She got up off the bed, hands on her hip, the tough posture ruined by her nudity as it served only to better display her boobs for me. "If you're not going to use me more, I'm gonna take a shower to clean up," she said, her words dripping with annoyance as she pointed to her crotch, where my cum was flowing out of her pussy and trickling down her leg.

I let out an exasperated sigh. Simultaneously annoyed that the rules seemed to have changed in ways I simply didn't understand yet, And aroused by the sight of her standing there completely naked while arguing me just like we always did. I had **** but to assume she was right, even if it went against everything I thought I knew. She was was really pretty when pissed and nude, but I didn't want to keep fighting her, so I tried to lighten the mood with a joke. "Fine, I can use you however I like? Well then, if I can use you to fuck me and not get pregnant, I can use you to fuck me and not have a mess afterwards," I put in lamely, playing to my sense of impossibility by saying something obviously ridiculous.

"Why didn't you just say that's how you wanted to use me?" she asked with an exasperated eye roll. The cum dripping from her pussy and the long streak of it down the inside of one though instantly vanished, along with the rest of the mess - our juices from my dick, the sweat on our bodies, and fluids staining the bed. Everything was suddenly perfectly clean, or at least as clean as it had been before, as if nothing had happened. "Are you was done being weird now? Obviously you can use me that way if you want," she put in, crossing her arms beneath her bare breasts. "I don't get why you are making a fuss about obvious things."

After watching us suddenly go from covered in sweat and cum to clean instantly just because I said so, all I could do was sit there, stunned.

"So, are you gonna use me more?" she again asked casually, turning to pick up her clothes, giving me a spectacles view of her bare ass and naked pussy as she bent over. "Or can I get back to my homework?" she continued, turning and leaning against her desk, inadvertently posing sexily for me, shoulders back, nude breasts thrust out. "I was planning to start right after I got off the phone, and I don't have time to deal with any more of your weird questions right now."