A couple of years ago, my brother-in-law and wife took their 16-year-old daughter and 12-year-old son away with them on vacation. They gave me a set of house keys, to check up on the place whilst they were away. They left on the Saturday morning and I went round there that evening, to ensure the place was secure. Whilst there, I thought I would check the laundry hamper for my niece's underwear, only to find it empty. I crept up to her room and checked her pantie drawer and found several pairs of ordinary white cotton panties and one very sheer pale blue thong, tucked right at the back. I took this downstairs with the intention of 'borrowing' it for the week, and returning it before they came back from vacation.
On passing through the kitchen, I noticed their empty washing basket in front of the washing machine. So, I opened the washing machine door and saw some dirty laundry inside, ready for washing on their return. Amongst some shirts I found what I had visited for. A pair of lilac, lacy boy pants which obviously belonged to my niece. Having been in the confines of the washing machine they were still slightly damp from when she had taken them off that morning. I lifted them to my face and smelled that heady aroma of pussy, which instantly got my cock hardening.
Thinking that I wouldn't be able to last until I got home, I returned to her bedroom and stripped naked. Holding her panties to my nose I slowly began to stroke my cock, imagining her pussy in front of my face. I slipped on her blue thong, which being too small for me, meant my cock was pressed tight to my stomach as I rubbed myself through the material. My purple head was now leaking pre-cum through the sheer nylon as I continued to rub my cock and sniff her panties. I could feel my balls tightening as my orgasm approached until I unleashed my man-juice through the material of the thong, making it slippery and more sensitive. My orgasm was more intense and seemed to last minutes rather than seconds, and my legs shook as I made a mess of my cock in the thong. As my orgasm subsided I removed the thong, cleaned myself up and took my 'trophies' home for use later in the week.