When I was younger and still lived at home, I lived out in the country and we had a barn and animals. During the summer when I was off from school I had to go out and feed them, clean up, etc. During one of the summers it was unbearably hot, so I was already wearing as little as possible. When it was time to go out, I decided to put on my overalls with nothing underneath and my flip flops.
I went out to the barn and started feeding the animals, and I was already starting to sweat. After I was out there for about 20 minutes I was drenched, but I was wet for a different reason between my legs. The denim was damp and was sticking to my naked vagina, and the seam riding against me was making me cream like crazy. I hadn't masturbated in a few days, and I needed it.
I finished as fast as I could, and by the time I was done, between my legs was nothing but a big wet spot of sweat and my own juices. I started to walk back towards the front of the barn, but I had to cum then and there. I walked back across a hay pile and found a nice spot, unbuttoned my straps and pushed off my overalls leaving me bare-ass naked. As soon as the fresh air hit my sopping wet vagina, I couldn't help but let out a loud 'ahhhhhh' because it sent shivers throughout my body. I grabbed a couple pieces of hay and started tickling my clit with it, and I almost came instantly. I held off and just started rubbing myself hard and fast. I came like never before, a stream of wetness rolled down between my cheeks and I was squeezing the hay between my toes.
I just lay there in peace for a couple minutes before I went to go back inside, but when I went to put my overalls back on they were absolutely uncomfortable, so I just got into my flip flops and walked back to the house naked. I took a shower and masturbated again under the water, and then one more time when I got back to my room.
After 10 years I can honestly say, I don't think I have been hornier or wetter than that day.