This happened on Sunday night when my sister in law stayed overnight.
This happened last night, and I'm still so blown away by it that I have to write it down.
My sister in law, Debbie, 43, stayed overnight at our house after travelling back from visiting relatives. This is a regular thing, so she stays often.
I get on really well with her. We laugh and joke but nothing sexual has ever been suggested between us.
Debbie is 5 foot 4 inches tall. Shoulder length dark blonde hair, a UK size 12. Small waist and has the most amazing 38gg breasts. Over the last few years she has lost a fair bit of weight, but none has come off her tits!
By the way, I know her sizes as I have a panty fetish so have been through her overnight bag on many occasions.
Anyway, I've been on late shift all over this bank holiday weekend, and got home from work around 11.30pm last night. I was feeling real horny, but knew that my wife wouldn't be accommodating sexually to me as her sister was in the room next door. I'd been up to my bedroom, and my wife was fast asleep anyway!
I grabbed my wifes worn knickers from the laundry basket and headed downstairs to the sofa for a nice slow wank and sniff with them, as I flicked through the tv channels to find a nice sight to wank off to.
I was engrossed in a chat channel where a young woman with big tits was trying to look seductive. Her body and the scent of my wifes cunt had my cock solid and sticking out through the front of my boxer shorts.
I'd probably been wanking for around 10 minutes, when I noticed a pair of legs coming down the stairs and into the living room. I panicked and attempted to put my cock away, hide the dirty knickers, and switch over the channel all at the same time. I failed on every part!
There stood Debbie, my sister in law, with a sleepy look in her eyes, looking straight at me, trying to take everything in.
I muttered my apologies, saying something along the lines of, 'it's not what you think.'
Of course it was exactly what Debbie was thinking!
She looked at me and started to giggle. She went and sat on a chair opposite me, and in a hushed voice said, 'Are they my sisters knickers?'
I cringed and replied that they were.
Debbie told me to carry on. I muttered that I couldn't, to which she replied that she'd like to watch.
I must add that Debbie was wearing a pair of night shorts and tee shirt.
I put my wifes dirty knickers back up to my nose and breathed in her scent. My hand started to slowly wank my rapidly hardening cock as Debbie looked between my knicker sniffing and my wanking.
Debbie stood up and said she'd be right back. I thought I'd blown it and she'd got freaked out, but within a matter of seconds of quietly going upstairs, she was heading back down.
As she crossed the living room, she threw her knickers at me and told me that she'd like to watch me smell hers.
Her face was flushed and I could see her nipples harden under her nightshirt.
I dont think I've ever been as horny as I was at that moment!
Her knickers were a black lacy short type, and as I opened them up to expose the gusset, I could see my sister in laws still damp pussy stains.
I put Debbie's knickers up to my nose and breathed deeply in. I'd smelt Debbie's pussy many times over the years, but this was something else. Possibly because she was watching me.
My cock was throbbing, I was scared to touch it in case I cum. She asked if she smelt good. I nodded my head, and decided to go for broke and pulled her knickers away from my face, showed her the slimy pussy stains, and then licked her pussy cream from them. Her eyes widened and she mouthed quietly that I was a dirty bastard.
I wrapped the knickers around my throbbing cock and wanked slowly, all the time looking Debbie in the eye. She kept her shorts on, but was rubbing herself ever so lightly as she watched me masturbate with her dirty knickers.
I could sense that I was going to spurt and told her I was going to cum. Debbie carried on looking at my knicker covered cock, and told me to, 'cum in them.'
As soon as she spoke those words, I began unloading my cum. I don't think I've ever cum like that before. I carried on wanking slowly until all my cum had been pushed out of my cock. I was laid back on the sofa, trying to catch my breath.
Debbie then stopped rubbing her pussy, stood up, took her cum filled knickers off of me, said Thank you, and went back upstairs to her room.
Nothing was said about it this morning when my wife was out of the room. I was as nervous as anything, but Debbie was acting normal.
I received a text late this afternoon from Debbie, and all it said was 'Thanks for last night. Our little secret.'
I just had to tell someone. Thanks for reading.