s****r In Law's Panties SeXStoRY

My wife's s****r Karen was coming to stay and I knew I was in for a couple of day's of fresh panty sniffing. I was tasked with picking her up from the airport and we chatted on the way home. When we arrived at our house she dumped her bag in the spare room and went straight out to see some old friends which gave me the chance to have a rummage through her bag to see what underwear she had brought with her. A couple of pairs of pink low cut panties and a couple of thongs. She returned a couple of hours later and announced she was taking a shower and changing into her pyjama's. Now from experience she would place her worn panties into a side pocket in her case and I wasn't disappointed when I searched her case the next day she was out. I went into her room and immediately went straight to the case which was laying on the floor half open. True to form the panties she had been wearing the previous day were in the case pocket folded in half. I lifted them out and opened them as I felt my cock twitch in anticipation of that sweet smell. They were a faded pink colour with a darker waist band and a motto across the back which read "cheeky monkey". I slowly opened the panties and tugged down the zip on my jeans and reached for my now hardening cock. With my bulging erection grasped firmly I raised the crotch of the panties to my nose and inhaled deeply. Oh god that smell of cunt made my heart race. I started to pump my swollen cock as I breathed in her dirty scent oblivious to everything around me including the sound of the door opening behind me. "What are you doing" was the first thing I heard which made me spin round to see Karen standing there. I dropped the panties and stood there with my cock stood to attention and leaking pre-cum. "Oh shit I am so sorry" I mumbled as she glared at me. She asked me how long I had been doing this and if my wife knew what I was upto. I told her it had been going on for a while and that no my wife, her s****r didn't know. Then out of the blue her face changed and she asked me if I wanted to sniff the panties she was wearing. I looked at her and asked her if she was serious at which point she lifted her skirt to show me the black lace thong she was wearing that I had seen on the day she arrived. My cock seemed to get even harder than before as I grasped it as I walked towards her. I kneeled down in front of Karen and leant forward and took a slow deep sniff of her thong. Dirty panties are fantastic but smelling them while she was wearing them was something else. As I knelt there she placed her hand on the back of my head and pushed my face into her warm slightly damp thong. I gently stuck out my tongue and began to lap at the soft material covering her mound. Still wanking my fat dick I raised my other hand and pulled the gusset to one side and slid my tongue up and down her wet cunt lips savouring the smell as it shot up my nose. She began to rub her cunt against my hungry mouth letting out small moans as I hungrily kissed her labia. She stopped, pushed me back and asked me to fuck her. I didn't need much encouragement and pushed her onto the bed. I lifted her skirt as she slipped off her by now sopping thong and handed it to me and told me to sniff it while I fucked her. Climbing between her firm thigh's she guided my cock into her slippery wetness as I pressed the thong to my nose and started to pump my stiffness deep into her. Her moaning and grunting as I fucked her as deep as my cock would go was making my balls tighten and I could feel I was about to cum. I looked her in the eye still forcing my shaft deep and asked her where she wanted me to cum. "In my cunt you dirty bastard" was her instant response and that was all she had to say. With one last hard sniff of her thong I started to ejaculate, thrusting hard with each spurt forcing my spunk into her as she gasped at how hot it felt inside her. I pulled out my softening member and then moved my face back to her cum soaked cunt and lapped up my spunk as it dribbled out of her. I dressed as did she and we both agreed what had happened would best be kept secret between us. The rest of Karen's weekend with us was pretty uneventfull save for her leaving her panties out for me when she went out. Hopefully we can repeat or little session but I think it may be a one off. Who knows....