Almost Caught With My Sister.

I could write an almost endless amount of stories about the many encounters with my sister, so here's one.
We were left alone too often after school for example, and this certainly made it easier for the two of us to fool around. This particular afternoon that I am taking about happened fairly late in the day. I randomly got horny after seeing her panties because she was sitting in a skirt with her legs open. I can't remember what I said, but she pulled her panties to the side, exposing her pussy in a playful and flirty way. That was all the encouragement I needed, and I was between her legs with my face, licking away (exactly as she liked it) at her tasty little pussy, while stroking my hard shaft with one hand. We were always conscious about our mother finding messy underwear, so I suggested we remove them. She agreed and lifted her butt enough for me to slip them off. Once they were removed, I wanted to be deep inside her, but she didn't want any penetration, which I was always respectful of, but she was keen on having me slide my rock hard throbber back and forth along her wet warm slit and clit. This went on for several minutes and I started to cum just above her pubic area. I was kneeling between her legs and a pool of jizz began to form on her lower stomach, just as we both heard our mother's car pulling into our driveway. I had no control over my situation, and couldn't stop what my body was doing, so I pretend that everything was fine for about 20 precious seconds, so I could finish cumming. My sister was obviously freaking out about me not hopping up and moving away. I quickly, but carefully got up as soon as I finished cumming, moving her legs together as I did. I then told her to not move as I lowered her skirt to conceal my my mess. The way she was positioned looked completely normal and the skirt wasn't even touching my load. I passed her panties from the floor, darted into the toilet, tucking myself into my pants as I did. I quickly grabbed toilet paper for the clean up my sister needed, just as I heard the front door open with my mother greeting my sister. I casually walked back into the living room saying hi to my mother as she headed to her room like clockwork to dump her bag and ditch her shoes. This gave us about 30 seconds to clean up. I handed my sister the toilet paper, and stood blocking the view from our parents room, just in case our mother was faster than normal. My sister quickly cleaned up my mess, passing the wet toilet paper back, and lowering her skirt again, just in time as our mother came back from her room.
I went and flushed the evidence just in time. My sister was so much better at acting normal whenever we had a close call. I was always super nervous to the point that I would almost be visibly shaking, so I'm glad one of us was at acting normal. We would usually get things over with much earlier in the day but time did regularly get away from us.
I will try to write down more of our close calls, as they were sometimes even closer than this one was. Yes, that's possible.
The sneaking around doing the most taboo of things, with my blood relative, is something that honesty made it all so exciting and fun, despite how wrong it was.