I've been reading (and loving) this site for a few years now. I only have one story of my own to post, though. It happened when I was about 15. I was at the public library, in the young adult section, when I decided to sit down in a chair and read for a while. The bookshelves were directly facing me, about 15 feet away.
I noticed this one guy, about 30, that kept hanging around the area. He was wearing a white t-shirt, and flimsy gray shorts made of sweatshirt material. His manner seemed a little odd but I ignored him until he did something that completely shocked me!
The bookshelf had a gap that was just at crotch level. He positioned himself in front of it, and started stroking himself... just kind of cupping himself in his hand and rubbing softly. If I were him I would have had a boner from the start, but I guess he wanted to deliberately work up to it. He continued that for a few minutes, and by the end I could see a definite bulge in his shorts. All the while he was stealthily watching me, his eyes just barely peeping above the books.
Then he wandered off for a little while, in an effort to look natural. But soon he was back. This time he rubbed up and down his semi-hard prick with the flat of his palm. This continued for about half an hour-- he stroked himself for a while, wandered off, and came back, getting stiffer all the while. His hard-on didn't diminish while he was meandering about the library, either. Anyone could see it poking up under his shorts. He wasn't wearing any underwear, nor did his shirt come down to cover it... there was *nothing* to hide it. All this was incredibly intriguing and exciting to me... I pretended to read my book, but I was crossing my legs and squirming in my seat, and discreetly pinching my nipples, trying to get off. I think what turned me on most was knowing that he was walking around knowing that people would be seeing his stiff dick through his shorts. It appealed to the exhibitionist in me.
The last time he came back, I could see his penis a mile away. It must have been about 7 inches. He wrapped his hand around it and jerked up and down the shaft right through the shorts. Within moments he stiffened, and I could tell that he had come (he must have put on a condom at some point, for neatness' sake). Shaken, I continued 'reading' for a little while longer and then left the library... I had a lot to think about. ;)