My girlfriend at the time K was about 5' 2' maybe 5' 5" straight light brown hair, pale skin, green or blue eyes (I forget it's been awhile) and she was around 90-105 lbs. She was a nympho any odd place to have sex we would even if her sister was there with us, but to be fair she was usually the lookout. I went over to her house Friday night and spent the night and we spent most of Saturday in her bed watching movies like Sex and Death 101 with her sister joining us sitting on the floor. We were partially nude and underneath the covers cuddling. She would wiggle her hips and press into my junk randomly until she reached behind her and grabbed my dick and began jerking me. To which I whispered in her ear "what about your sister? Will she care?" To which she replied in a whisper "what about her?" While giving me a wink and a tight squeeze. I shrugged and got out of my boxer briefs and laid on my back and acted like I was watching the movie. After a couple minutes of getting a dry rub she motioned for me to scoot up on her bed as she slid down on her bed. She began giving me head trying to throat as much of it as she could without making a noise until I involuntarily flexed. She make a little gagging noise and her sister slowly turned her head to us and said "don't think you'll convince me to join." Turned back to the movie and tried to ignore us. K got back up and got into spooning position while spreading a cheeck so I could get into her. K tried to stay quiet but every once in awhile a soft moan would slip out causing her sister to shush us. That went on for about 10-20 minutes until I finished on her butt cheek. "Are you two finally done?" Her sister asked after a few minutes of silence not wanting to turn around until she got the all clear.