A few weeks ago we had a visit from my mother-in-law. Of course being the perv I am I took full advantage. Several times over the last few years I've had chances to be alone in our house or my in-law's house for several hours at a time. As soon as I find out I'll be alone my cock starts to swell, knowing what's to come.
The first couple of times were at their house and I went straight to the panty drawer looking for anything slinky, silky, or stained I could get my hands on. In the beginning her selection was rather mundane, mostly cotton bikinis. But still, it was such a turn on that I'd run to the bathroom to jerkoff.
In more recent times though I've found more satin and silk string bikinis. Rubbing my cock with them is enough to send me into orbit very quickly.
During this last visit my wife and her mother left for the whole day. As soon as I felt they were down the road I rushed to the guest room. I opened her suitcase to find her usual cotton and satin bikinis, but on digging deeper was rewarded with a really skimpy thong, and a pair of hotpants with the whole crotch and ass cut out. My cock was already very hard at this point. I rubbed the thong in my face and under my nose for a bit while stroking myself with the silky hotpants. I kept this up for a few minutes wondering what she looked like in them and imagining how hot it would be if she asked me to do it in front of her.
The whole episode ended with me in the guest bathroom, pants around my ankles, lightly rubbing my balls, jerking my slick, pre-cum covered prick and shooting a massive amount of cum into the toilet with such force I could actually hear it squirting out.
Now I can't wait until the next visit.