I really enjoy the stories on this site, especially the MM mutual masturbation stories from older submitters.
Two weeks ago I was walking along a backwoods trail at a wildlife refuge in western New York.
At the intersection with another trail, I spotted the rusted remains of an old wood-burning stove and when I looked inside, I discovered a .50-caliber ammo box containing a logbook and some trinkets. It turns out I'd stumbled on a geocache, which people search for with GPS units.
Entries in the log went back to 2003, and since I didn't have time to read all of them, I decided to come back later and read the rest. Two days later I did just that, approaching on a different trail. But when I got within 100 yards of the geocache I saw I wasn't alone. A young man and woman were standing by the stove, locked in an embrace and a kiss. I froze. When it was apparent they didn't see me, I slipped behind a tree and got a closer look through my binoculars.
Strangely, the woman's arm nearest me wasn't wrapped around the man's neck or waist, but hung straight down. Then I noticed it was moving. The binoculars revealed the man's cock was protruding from his unzipped fly, and the woman's hand was wrapped around the shaft, making fast, jerking movements. After a few seconds, the woman shifted her weight as if she was about to kneel and give the man a blowjob to finish him off, but instead she simply moved to the side to avoid getting spattered by his cum.
Before I realized what was happening, the man flipped his cock back inside his pants, zipped up, and the two of them started walking directly towards my hiding place. I walked away as quickly and quietly as I could, keeping several trees between me and them. Then I turned around and started walking back towards them, as if nothing had happened. The man smiled and said 'Hi', while the woman followed him with her head down and said nothing.
When they were out of sight, I walked to the place where they'd been standing. Several wet glistening spots on the forest floor indicated I hadn't just imagined what I'd seen, but the real proof was a dime-sized spot of cum on a freshly-fallen leaf. It was already cold to the touch, and since I never really enjoyed the taste of my own cum, I couldn't work up the nerve to sample someone else's.
This was my first, and probably my last, experience as a voyeur, because it's not likely I'll ever stumble upon something like this again. But it's something I'll remember and use to fuel my fantasies for a long time to come.